题目内容：

有关定语从句的一道题
The place _______ interested me most was the Children`s Palace.
A.which B.where C.what D.in which
答案是B我选的是A,可是如果是B的话,"where"那就在从句中作为主语了,而where不是关系副词吗?怎么能充当主语呢?