求助2题PREP中的题目

看过解释了，可是还是不怎么清楚啊～

73.     (28457-!-item-!-188;#058&003634)

Evolutionary psychology holds that the human mind is not a "blank slate," but instead that it comprises specialized mental mechanisms that were developed as a way of solving specific problems human ancestors faced millions of years ago.

(A) the human mind is not a "blank slate," but instead that it comprises specialized mental mechanisms that were developed as a way of solving

(B) the human mind is not a "blank slate" but instead comprises specialized mental mechanisms that were developed to solve

(C) the human mind, instead of a "blank slate," it comprises specialized mental mechanisms that have been developed to solve

(D) rather than it being a "blank slate," the human mind comprises specialized mental mechanisms that have been developed as a way of solving

(E) rather than the human mind's being a "blank slate," that it comprises specialized mental mechanisms that were developed as a way of solving

这里not  but是形式不平行的，但是怎么看出是结构平行，什么叫结构平行呢？

这里理解成,并列句-----并列句主语相同,应该省略重复的主语, 这样MM就好理解了.
     

这里理解成,并列句-----并列句主语相同,应该省略重复的主语, 这样MM就好理解了.
     

这里理解成,并列句-----并列句主语相同,应该省略重复的主语, 这样MM就好理解了.

或者理解为应该是主语the human mind 后跟两个并列谓语is 和 comprises , but 在这里连词    

74.     (28503-!-item-!-188;#058&003635)

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

Prep上说这里的Cbut会有歧义，可是这个很形式平行啊。。not+名词，but+名词

就比如说not by...but by形式很对称的。为什么要加Are。感觉加了are不平行了。

请指教。。