After five hours’ drive they reached they thought was the place their parents had lived m

问题补充：

After five hours’ drive ,they reached they thought was the place their parents had lived many years ago .

A. that

B. where

C. which

D. what

答案：

A. that

B. where

C. which

(答案→)D. what

解析：What they thought是reach 后面的宾语从句中的主语部分。