求助 一道SC,大家帮忙看看

The number of undergraduate degrees in engineering awarded by colleges and universities in the Unite States increased by more than twice from 1978 to 1985.

a) increased by more than twice

b) increased more than two times

c)  more than doubled

d) was  more than doubled

e) had more than doubled

答案选 C , 但是 没有谓语动词啊  D 为什么不对呢? 大家帮帮忙吧