prep1-149

149.      (32963-!-item-!-188;#058&006488)

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

从对称上能选出答案D，可是怎么翻译呢？看不明白scientists believed that 
cells either secreted hormones, in which case they were 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.

也就是believed that the cells either.........or...........（我怎么在这个宾语从句里找不到谓语！）太白了，自己。

有没有好心人路过，帮着看看，谢谢！