GWD-8-Q39:

Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes form a random pattern.

A. Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes

B. Whereas the tiny tubes for the conveying of nutrients to bone cells are arrayed in mammals in parallel lines, birds have tubes that

C. Unlike mammals, where the tiny tubes for conveying nutrients to bone cells are arrayed in parallel lines, birds’ tubes

D. Unlike mammals, in whom the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, the tubes in birds

E. Unlike the tiny tubes that convey nutrients to bone cells, which in mammals are arrayed in parallel lines, in birds the tubes

answer(A), but why?

A. Whereas in mammals....the tiny tubes ... are arrayed, in birds the tubes form....

whereas 引起对比，主、从句结构对称

B. 冗长、结构不对称

C\ D 用mammals 和 birds' tubes比较，错误

E. Unlike the tiny tubes that convey nutrients to bone cells, which in mammals are arrayed in parallel lines, in birds the tubes

说不清楚，Unlike the tiny tubes that...., which in mammals..., in birds the tubes...比较别扭

不知道这样讲有道理没？