After five hours’ drive they reachedthey thought was the place they’d been dreaming of.At

问题补充：

After five hours’ drive, they reachedthey thought was the place they’d been dreaming of.

Athat Bwhere Cwhich Dwhat

答案：

解析：D引导词引导宾语从句，作及物动词reach的宾语，又因引导词作was的主语（they thought为插入语，对句子结构不产生决定性的影响），所以引导词要用what。