It worried her a bit _____________ her hair was turning grey

It worried her a bit _____________ her hair was turning grey

A.which

B.that

C.if

D.for

答案及解析： B

解析：

主要测试主语从句。分析句子结构可知句子中用了形式主语it，句子的译文为：她的头发逐渐变白让他非常担心。答案为B。