2001-05-13语法

以下是引用joywzy在2004-1-9 22:09:00的发言：
13,Fossils, traces of dead organisms found in the rocks of Earth’s crust, reveal ----at the time the rocks were found.
A. what was like
b. was like life
c. what life was like
d. life was like
ans:C, I choose A,what 的用法

A中，WHAT作代词，为何不对啊？在C中，作为形容词？不明白，能讲讲吗？

谢谢。