XYZ, aquatic mammals inhabiting Florida’s rivers and coastal waters

What I like about CR is the feeling of sudden awareness that an answer choice is correct; everything just clicks into place.

With this question, there were no clicks. In fact, I found (E) to be WEAKENING the conclusion. Of course no other answer choices worked, but we can't work by default here, and choose the answer choice that is most relevant to the prompt (in this case (E).

But just to run a little experiment, let me argue for (E) to illustrate what I must do in order to make this answer choice work.

(E) says that XYZ cannot tell the difference between low-pitched and high-pitched sounds. But a slow boat spends more time moving across a body of water, so that gives XYZ more time to collide with it. Therefore, slow boats are more dangerous.

That answer may seem sensible, but I am doing a few things you should never do on GMAT Critical Reasoning. First off, I am discounting part of the conclusion, which states: slow boats are more dangerous to XYZ than are fast boats, because XYZ cannot hear slow boats.

Secondly, I am making some inferences that are not backed up by the passage (and indeed may not be backed up by reality). Namely, that XYZ is more likely to collide with a slow moving object.

Here nothing is "clicking into place," and I have to really labor to come up with an answer. The less straightforward the reasoning the more likely the given answer choice is wrong.

So it is only by breaking rules fundamental to GMAT that I can conceivably make (E) work. So (E) is definitely NOT the answer

The question--which I like, besides the prosaic tag XYZ (couldn't we just say hu-manatee)--is therefore broken. To fix it, all we would need to do is to add the word WEAKEN to the question. As in:

Which one of the following would WEAKEN the conclusion.

Then, the answer is clearly (E). The conclusion states that XYZ is likely to hear low-pitch than high pitch. (E) says that XYZ is unable to determine the difference).

So again, there is NO ANSWER to the question. It is faulty, but can easily be emended by the addition of one word.