Top Law Schools

I don't understand how A resolves it. I read the solution on LSATHacks and I still don't get it. I can understand how B, what I chose, is incorrect.

I surmise I could get to A by POE but still. I just don't see how A resolves the paradox of how the dragonfly population is more likely to remain healthy in areas with crayfish than in areas without them.

Thanks

I can kinda see how A is right but mann you gotta bring in a lot of extra assumptions to justify A. Anyone have anything to add to clarify A as the correct answer choice?

I think B is correct.

WordPass wrote:I think B is correct.

it's a

Q was about crayfish and dragonfly

The question you referred to in your title is not the same question you're referencing in your post ...or maybe by LR II did you mean the second logical reasoning section?

WordPass wrote:The question you referred to in your title is not the same question you're referencing in your post ...or maybe by LR II did you mean the second logical reasoning section?

yea. Normally I would have said 2nd LR section but I don't want people getting confused because the 1st LR section is section 2 of the test. I'll update the title

In any event, for the crayfish question, I was down to A and B as well.

The surprising fact is that despite the fact that the dragonflies are eaten by red devil crayfish, they still are more likely to remain healthy in areas they are present. Well, what could account for this fact? There could be a bunch of things and if nothing jumps out at me, then I generally keep in mind that there needs to be something positive about the crayfish (or whatever the subject is) or something we aren't considering.

The first thing that makes Answer Choice B fishy is that they talk about the adult population when the stimulus mainly references the larvae population. Not a problem in and of itself, but there's reason to be suspicious. When we look deeper into it, we see the larvae population can only survive in water and they are the ones subject to predation by the red devil crayfish. So, in essence, answer choice B doesn't tell us that much of anything. I mean, it's certainly possible that they pose no threat to the adult population, but the stimulus never even disagreed with that and it's possible that they account for this fact. We want to look for something that truly impacts the argument and this one doesn't tell us much.

Another reason answer choice B is wrong is that the "surprising fact" is that these dragonflies are more likely to remain healthy. Healthy being the important part. We want answer choice that again, really ties this in. The fact that they pose no threat to the adult population doesn't really tell us much about health (versus surviving/dying that answer choice B mainly alludes to).

For Answer Choice A, this really gets at what we are trying to explain. We know that they can only survive in water. Not air, not dirt, water. They need it. The red devil crayfish digs up places that fill up with water when everywhere else is dried up (which tells us that the dragonfly larvae would have a hard time surviving there) and this is what would help explain why the dragonfly population would remain healthy in these parts.

If you're taking the test tomorrow, good luck! I am too and I'm trying not to shoot myself. Hope this helps.

WordPass wrote:In any event, for the crayfish question, I was down to A and B as well.

The surprising fact is that despite the fact that the dragonflies are eaten by red devil crayfish, they still are more likely to remain healthy in areas they are present. Well, what could account for this fact? There could be a bunch of things and if nothing jumps out at me, then I generally keep in mind that there needs to be something positive about the crayfish (or whatever the subject is) or something we aren't considering.

The first thing that makes Answer Choice B fishy is that they talk about the adult population when the stimulus mainly references the larvae population. Not a problem in and of itself, but there's reason to be suspicious. When we look deeper into it, we see the larvae population can only survive in water and they are the ones subject to predation by the red devil crayfish. So, in essence, answer choice B doesn't tell us that much of anything. I mean, it's certainly possible that they pose no threat to the adult population, but the stimulus never even disagreed with that and it's possible that they account for this fact. We want to look for something that truly impacts the argument and this one doesn't tell us much.

Another reason answer choice B is wrong is that the "surprising fact" is that these dragonflies are more likely to remain healthy. Healthy being the important part. We want answer choice that again, really ties this in. The fact that they pose no threat to the adult population doesn't really tell us much about health (versus surviving/dying that answer choice B mainly alludes to).

For Answer Choice A, this really gets at what we are trying to explain. We know that they can only survive in water. Not air, not dirt, water. They need it. The red devil crayfish digs up places that fill up with water when everywhere else is dried up (which tells us that the dragonfly larvae would have a hard time surviving there) and this is what would help explain why the dragonfly population would remain healthy in these parts.

If you're taking the test tomorrow, good luck! I am too and I'm trying not to shoot myself. Hope this helps.

Thank you. This helped

A.Taarabt7 wrote:I can kinda see how A is right but mann you gotta bring in a lot of extra assumptions to justify A. Anyone have anything to add to clarify A as the correct answer choice?

Synthesizing the information in the first sentence of the stimulus ('...are an endangered species that live in wetlands') together with the rest and properly interpreting the meaning of the last sentence ('populations are more likely to remain healthy') is critical for properly understanding what the apparent paradox/surprising fact you need to explain actually is and for being able to see/understand the logic of how (A) helps explain it.

Since the first sentence tells us that the dragonflies are an endangered species, the proper contextual meaning/interpretation of the last sentence is that the populations of the emerald dragonflies are more likely NOT to significantly SHRINK/DECREASE in wetland areas where red devil crayfish also live.

Although the word 'healthy' in most contexts does mean that the thing(s) are in good health rather than being sick (not healthy but still alive), in the context of this sentence and stimulus, 'populations...remain healthy' is talking about the population sizes of the emerald dragonfly species in those wetland areas, meaning that the populations aren't dramatically decreasing/heading closer to extinction (remember, we are told in the first sentence that they are an endangered species). It is NOT telling you that the dragonflies living in those areas with the devils are in great health as opposed to still being alive but just not being 'healthy' dragonflies. The key here is that 'healthy' is referring to the 'populations', meaning groups of members of the species, not to the individual dragonflies themselves nor to the relative states of 'health' of the individual living dragonflies, nor to the average level of physical/bodily health of the population groups of dragonflies living in different wetland areas where the devils also live.

In this question, like many other hard LR questions from recent years, the test writers are partly testing critical reading, grammar and vocabulary skills/knowledge. 'Healthy', like tons of words in the English language, has several different valid meanings/uses where the full context the word is used in dictates it's specific meaning in the context it's being used. One valid adjective definition/meaning of 'healthy' is "fairly large, a large amount" (Example: 'I bought a healthy number of textbooks'), and that is the definition of 'healthy' that applies to the last sentence of the stimulus given the context of the stimulus established by the 'background information premise' first sentence combined with the phrasing of the last sentence where 'healthy' is referring to the 'populations', meaning groups of members of the species.


For a population to stay healthy (not die off/diminish/go extinct!), the species must be able to reproduce at at least the same or a higher rate than the death rate within the population. The second sentence tells us that water is necessary for the dragonflies to reproduce since the larvae need water to live in order to subsequently grow into adult dragonflies to keep the species alive and in existence. That sentence also tells us that the larvae are subject to predation by several species including the crayfish because the larvae live in the water. That doesn't establish/guarantee that all the larvae will be eaten by the predators, the logical force is much weaker than that, 'subject to predation' establishes that they are vulnerable and MIGHT get eaten by the predators. This leaves open the possibility that many larvae living and growing up in the same water where crayfish and other predators live/hunt do manage to avoid getting eaten by them and successfully grow into adult dragonflies, thus contributing to the size of the dragonfly population with a new generation of offspring. Being 'subject to' something happening to you doesn't mean it will necessarily happen to you. It does indicate there's some degree of probability of it happening, but also allows for the possibility of it not happening, meaning many larvae can manage to avoid getting eaten by the predators and grow into adult dragonflies.

So, our paradox/surprising fact we need to explain is why are the endangered dragonfly populations more likely NOT to decrease/get closer to extinction in areas where their offspring have to grow up in water that also contains predators that like to eat the dragonfly babies (larvae)?

The weak logical force of 'subject to predation' discussed above by itself leaves open the possibility that a bunch of the larvae do manage to avoid getting eaten and mature into adult dragonflies to add to the population, and the last sentence establishes that lots of them DO escape getting eaten while in larvae form since we're told that the populations remain healthy in those areas. So how the heck is having a bunch of crayfish around that want to eat your babies and are thus a threat to population growth helpful to maintaining a healthy population size? Aside from being meanies that like to eat the dragonfly babies, the crayfish must also do something that benefits the dragonflies in a way that enables them to maintain good population sizes that do not decline further towards extinction.

(A) Tells us the good thing the crayfish do that helps the dragonflies reproduce and avoid going extinct.

Notice that (A) is a conditional statement, 'when' is a sufficient condition indicator.

When wetlands dry up (NO H2O to grow larvae in!) ---> the devil crayfish come to the rescue by digging holes that fill with water, thus giving a place for dragonfly larvae to live and grow into adult dragonflies. Without the crayfish digging water filled chambers where larvae can live and grow, the dragonflies wouldn't be able to reproduce when wetlands dry up since their larvae require water to survive and the dragonflies, as we're told in the first sentence, live in wetlands.

Obviously some, probably many of the larvae do get eaten and never become adults to add to the population, but enough do to keep the populations at a healthy size, thus keeping the endangered species from going extinct.

In short, the crayfish help prevent the dragonfly populations from getting wiped out/significantly diminished in size due to droughts that could otherwise prevent them from reproducing and creating more dragonflies to keep the species alive when the wetlands they live in dry up. If/when the wetlands dry up, the dragonflies would otherwise be F*cked and not able to reproduce/have any babies that survive/larvae grow into dragonflies to carry on the species without at least some places in the wetlands with water for larvae to live and grow up in to become dragonflies. Even just one bad drought year/season where the wetlands dry up could wipe out an entire population in an area or perhaps even the entire species by preventing it from being able to reproduce another generation of dragonflies, leaving none left if all the currently living adult ones die without having produced any larvae that survived and grew into being adult dragonflies that could then reproduce and continue existence of the species when it rains again.

Make sense?