再问大全404

404.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
这里为什么要用what it was in呢？
难道B不够工整么？