The number of undergraduate degrees in engineering awarded by colleges and universities in the United States increased by more than twice from 1978 to 1985.
The number of undergraduate degrees in engineering awarded by colleges and universities in the United 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
the best answer is C, I wondered, what part does "more" act as here?