PREP07 SC的73怎么能平行呢？？！！求分析

zhangjiao1025

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
答案是D，为什么不是C？？

cyz12321

are not.....,(favored because......)but are......
favored那句当成插入语看。
C句末少了are，连词结构不对称了~