一道题的总结加我的疑问

取巧

GWD6-Q31:
The fact of somefraternal twins resembling each other greatly and others looking quitedissimilar highlights an interesting and often overlooked feature offraternal-twin pairs, namely they vary considerably on a spectrum of geneticrelatedness.

A.     The fact of some fraternal twins resembling each othergreatly and others looking quite dissimilar highlights an interesting and oftenoverlooked feature of fraternal-twin pairs, namely they vary considerably
namely加名词    The fact of +n+diong不好，而一般thefact that
B.      That some fraternal twins resemble each other greatly whileothers look quite dissimilar highlights an interesting and often overlookedfeature of fraternal-twin pairs, namely that they vary considerably
C.     With some fraternal twins resembling each other greatly andothers looking quite dissimilar, it highlights an interesting and oftenoverlooked feature of fraternal-twin pairs, namely considerable variation
    With结构是独立主格结构
D.     With some fraternal twins resembling each other greatly andothers looking quite dissimilar, it is a fact that highlights an interestingand often overlooked feature of fraternal-twin pairs, namely a considerablevariation
E.      Because some fraternal twins resemble each other greatlyand others look quite dissimilar, this fact highlights an interesting and oftenoverlooked feature of fraternal-twin pairs, namely they vary considerably
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答案是B，谁能解释一下C和D？
Namely用法：
Namely就是一一列举
Namelythat
Namely+n
Namely+todo

lala974

c it指代不清