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How did I screw this up?

For the stimulus I had:
1. -ancestors motivated by desire to sacrifice themselves --> -humankind survived (original first sentence)
2. humankind survived -->ancestors motivated by desire to sacrifice themselves (contrapositive of first sentence)
3. humankind survived --> ancestors' sacrifice --> altruism (contrapositive connected to second sentence)
4. Therefore, ancestors at least partially altruistic. This doesn't connect the first element in the chain of logic (humankind surviving) to altruism, it only deals with the second and third links.

None of the other answers come close to following this logic, but I don't see how A is correct. This is how I'm diagramming A (it's much more straightforward than the stimulus):
1. -increase time spent studying --> -raise grades
2. raise grades --> increase time spent studying --> good time management
3. some students do raise their grades, therefore, some students manage their time well (flows from link 1 to link 3 down the chain)

Is A correct because the question asks which argument is "MOST similar" in its reasoning? (If so, that's crap.) Or did I just fuck up my stimulus diagram?

Was still thinking about this before I fell asleep and had this thought - is it because we are told at the beginning of the stimulus that humankind has clearly survived that the logic goes from link 1-3, like answer A? I just need someone to tell me which of these reasons so I can fall asleep more quickly tonight!