求助一道prep上的题目。

lovejady

43. Paleontologist Stephen Jay Gould has argued that many biological traits are not the products of natural selection, favored due to their enhancement of reproduction or survival, but that they are simply random by-products of other evolutionary developments.

A due to their enhancement of reproduction or survival, but that they are

B due to the reproduction or survival they enhance, but they are

C because they enhance reproduction or survival, but

D because they enhance reproduction or survival, but are

E because of enhancing reproduction or survival, but are

我觉得应该是not...but...的对称结构。可是给出的答案是 D,请高人指点

胡搅蛮缠

I picked C too...

遥远的绿洲

C选项会产生歧义:

enhance reproduction or survival, but simply random by-products

7barbara1986

个人认为，因为那个but are后面的句子是和前面are not the products of natural selection这个句子平行的~~~而那个favored
    because they enhance reproduction or survival是修饰the products of natural selection对其作解释,所以选D

lovejady

同意4楼的分析，就是因为是not..but...的平行结构，所以才不能在后面加谓语动词are,