求助替代词that的一个知识点

stringr

prep2008的语法笔记里面写：
that作为替代词，不能用于零关系分句(即没有关系代词的定语从句)之前。
ex: The problem confronting us today is not dissimilar from that which the nation confronted in the 1930s.
我的理解是，如果that作为替代词需要定语从句修饰的话，需要加which。

但在OG2016 SC#48一题中，D选项的that which被认为是incorrect English.
Digging in sediments in northern China, evidence has been gathered by scientists suggesting that complex life-forms emerged much earlier than they had previously thought.
(A) evidence has been gathered by scientists suggesting that complex lifeforms emerged much earlier than they had
(B) evidence gathered by scientists suggests a much earlier emergence of complex life-forms than had been
(C) scientists have gathered evidence suggesting that complex life-forms emerged much earlier than
(D) scientists have gathered evidence that suggests a much earlier emergence of complex life-forms than that which was
(E) scientists have gathered evidence which suggests a much earlier emergence of complex life-forms than that
OG对D的解释：D In this context it would be preferable to use a verb (emerged). The phrasing used here (suggests a much earlier emergence of) sounds more stilted and is less clear and direct. In addition, inserting that which before previously thought is not only redundant but incorrect English.

为什么在OG这道题that which又是不行的呢？

stringr

别贝尔 发表于 2016-9-5 18:08
楼主你写的这句话 The problem confronting us today is not dissimilar from that which the nation confr ...

感谢回复！

OG的D选项get！

The problem confronting us ... 一句是正确的，CD里亦有提及，请见http://forum.chasedream.com/thread-499224-1-1.html
也出现在赵振才《英语常见问题解答大词典》2002版第949页，截图如下：

别贝尔

楼主你写的这句话 The problem confronting us today is not dissimilar from that which the nation confronted in the 1930s.是正确句子嘛？which要么是comma which，要么是prep+which结构，如果这个句子正确的话，那是from which这种结构？

that不能单独作为代词使用，比如你举例的OG题目里。OG16的88题D答案也有这个错误
that作为可以作为代词的情况是在比较结构中 the economy of country x is stronger than that of country y.


而且在D中that是指代谁呢？指代后面的想法？如果楼主理解的是指代后面的话，那样就redundant了呀，直接说previously thought多简洁