GWD6－Q31一个大家始终回避的问题

Q31:

The fact of some fraternal twins resembling each other greatly and others looking quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably on a spectrum of genetic relatedness.

1. The fact of some fraternal twins resembling each other greatly and others looking quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably
   
2. That some fraternal twins resemble each other greatly while others look quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely that they vary considerably
   
3. With some fraternal twins resembling each other greatly and others looking quite dissimilar, it highlights an interesting and often overlooked feature of fraternal-twin pairs, namely considerable variation
   
4. With some fraternal twins resembling each other greatly and others looking quite dissimilar, it is a fact that highlights an interesting and often overlooked feature of fraternal-twin pairs, namely a considerable variation （B）
   
5. Because some fraternal twins resemble each other greatly and others look quite dissimilar, this fact highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably

这题前面的讨论贴有不少，一一翻过，发现好几位XDJM们都问过这个问题，却没有相应答复，偶觉得还是比较重要的，所以特别提出来再求教

本题中正确选项B中的namely that they vary considerably，这个they好像有指待不清之嫌呀，到底指待谁呢。。。

期待解答

可是这个是按我们的逻辑判断的，但就语法来看是否其指代有问题呢？they前面出现两个复数名词

They are in another clause.

我也搞不懂。注意到只有B项namely后面有个that，这个that什么意思？？？？？？？？？？？

a. the fact of 不对，应该用同位语结构

d. it is a fact that highlights  wordy

e.because引入原文没有的因果关系

剩下b和c我想了一下，还是选b了

c选项中，it无指代对象。而且，considerable variation做同位语，不知道是feature还是fraternal-twin pairs的同位语

ps：namely是副词，意思是“那就是说；明确地”，相当于that is to say，就把namely当插入成分拿掉吧。

那个they，我也只能从逻辑上确定它指代的是twins，语法上貌似有点指代不明