I don't understand why B is the correct answer choice for this question. I wasn't happy with any of the answer choices but ultimately ended up picking D. Here was my reasoning for eliminating all the other choices.
(A) The whole passage is about neurogenesis so eliminating this one was easy.
(B) Aah! I eliminated this one because of the information provided in the third paragraph. Specifically lines 30-33 and 43-47. The only reason I can think for this being the correct answer choice is that the author doesn't explicitly talk about the body weight of canaries but rather just about the size of their brain.
(C) Supported by lines 55-58.
(D) Since the second paragraph talks about how long the memory of the repertoire of song for canaries last, this was easy to eliminate too.
(E) Finally, since the second paragraph also talks about the canaries learning how to sing. It was easy to imagine a parallel between this and humans learning complicated tasks.