Preptest 47, Sec. 1, Q12 Forum

[TheDudeAbides2011]

I'm usually ok at these types of questions, but for some reason I'm stumped. I have 2 questions:

1. What is the assumption that is made in this passage?

2. I can kind of see why E is the correct response, but I would like to know why I should eliminate A.

Any help would be greatly appreciated.

[Cambridge LSAT]

Using the context of the conclusion, we can extract two conditional statements from the premise:
human life --> matter X + carbon based + genetic code
all other known life --> matter X + carbon based + genetic codes

And here's the conclusion:
Origin (Human) = Origin (Other)

Choice E connects the basic types of matter to origin, and creates the following:
human life --> matter X --> Origin <-- matter X <-- all other known life

Note that there are two additional sufficient assumptions which could have completed the argument.
1) Any two living things which are carbon based have the same origin.
2) Any two living things which have genetic codes have the same origin.

Choice A, on the other hand cannot be plugged into the argument to complete it:
human life --> other life forms

[jasonhmann]

Well the logical gap I would say is origin, since the premises or evidence never discusses that. I would look for an answer choice that discusses both origin and matter or genetic codes.

A) out of scope, doesn’t matter if we exist or not, we need something to establish ORIGIN to human life.
B) if this does NOT occur we can still have the same origin since. For example ORIGIN is rated by genetic codes.
C) this does NOT occur we can still have the same origin since. For example ORIGIN could be related by same basic kinds of matter
D) outside, don’t care about yet to be discovered
E) Yes, ties to the origin to basic kinds of matter and is the winner

[jasonhmann]

I missed Cambridge's response and I like it,

Note that there are two additional sufficient assumptions which could have completed the argument.
1)Any two living things which are carbon based have the same origin.
2) Any two living things which have genetic codes have the same origin.

My experience with the LSAT is on assumption questions, look at the conclusion for the missing piece, which is origin to the evidence.

Good job Cambridge!

[TheDudeAbides2011]

Thanks to both of you for your responses on this. I think I understand it now.