Q15 - Hine's emerald dragonflies are an endangered species

[yisiyu123]

I can see why the four other answer choices are incorrect, but why A helps explain the fact?

Is it because the chamber filled with water can more or less provide the larvae with water to survive?

Doesn't it require us to have a certain knowledge that in wetland water is rather sacred so the larvae would have better health around red devil crayfish?

Could any LSAT geek please help me?

[maryadkins]

Is it because the chamber filled with water can more or less provide the larvae with water to survive?

Doesn't it require us to have a certain knowledge that in wetland water is rather sacred so the larvae would have better health around red devil crayfish?

Yes, that is why! Good job.

It doesn't require outside knowledge because in the stimulus we are told that "the larvae of these dragonflies can survive ONLY IN THE WATER." (A) tells you that the chambers with water exist thanks to the crayfish "when the surrounding wetlands DRY UP." So you don't even have to infer, because you're told:

1. There isn't water around.
2. But there is in the chambers, due to crayfish.
3. And the larvae need this water.

(A) is the only answer choice that explains the paradox.

As for the others:

(B) Okay, but they ARE to the larvae and that's what we need explained.
(C) Okay...so then why are there more DFs when the RC are around?
(D) Great! Irrelevant!
(E) This tells us that RC aren't so dependent on DFs but it doesn't help us understand why the paradox.