Prep149极 困惑的一题，求解释，求解释，求解释

Outsider1988

Until Berta and Ernst Scharrer established the concept of neurosecretion in 1928, scientists believed that either cells secreted hormones, which made them endocrine cells and thus part of the endocrine system, or conducted electrical impulses, in which case they were nerve cells and thus part of the nervous system.

(A) either cells secreted hormones, which made them

(B) either cells secreted hormones, making them

(C) either cells secreted hormones and were

(D) cells either secreted hormones, in which case they were

(E) cells either secreted hormones, which made them

OA is D
尽管蒙对了，对句子结构很不解，我怎么觉得句子少了谓语，怪怪的
句子的整体结构不是Until..., scientists believed that cellls either...,or...吗？？？
哪that后面的句子的谓语呢？？？
还是我这个语法白痴结构就弄错了？？

求解释
。。。

magicinair

谓语是secret & conduct...

Outsider1988

got it
谢谢LS的
我还以为cells secreted hormones跟conducted electrical impulses是个什么学术词汇
没仔细看
谢啦