[求助]大全885B-21请教大家

 A  peculiar feature of the embryonic mammalian
circulatory system is that in the area of the heart the cells adhere to one
another, beating in unison and adopting specialized orientations
exclusive of one another.E

(A) beating in
unison and adopting

(B) they beat in
unison while adopting

(C) beat in
unison, and adopt

(D) beating in
unison yet adopting（D）

(E) even though
they beat in unison and adopt

我有两个疑问，一个是E，为什么不行，是语法，还是句意；还有一个就是C和D的区别，有位NN讲

D.

Here we need to have a contrast. The word "and" is incorrect in the underlined sentence and hence needs to be replaced with something like while/but/yet etc.