[求助]白勇语法 p204页 36题

In the 1980's the rate of increase of the minority population of the United States was nearly twice as fast as the 1970's.

A  twice as fast as   B  twice as fast as it was in

C twice what it was in D two times faster than that of

E two times greater than

答案是C，但是B是否也正确？ 书上说在从句主语和谓语动词如果和主句相同可省略，这里用it带指主句主语 the rate of increase 是否也可以呢？

望各位牛人给个指点，谢谢！