Explanation on A

This is a Cannot Be True question so we are looking for an answer choice that conflicts with the stimulus. There is nothing in the passage that conflicts with (A), i.e. "Crows will abandon their roost site only in response to increases in the population of the flock." This could be true as the reason for abandoning a roost site is never even mentioned in the stimulus. Hope that helps! Please let us know if you have any other questions.

I also am having difficulty accepting E as the correct answer choice in comparison with A. A has an "only" statement, wouldn't that be considered a stronger statement than E since it uses "generally"? With your explanation, couldn't E also be considered true? I am having more difficulty accepting A as a could be true answer choice because it's not that difficult to imagine another situation besides population growth that would cause the roost to relocate, for example, their roost site could have been destroyed by a fire or a tornado.