[求助]prep上一道比较题

181.
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The number of people flying first class on domestic flights rose sharply in 1990, doubling the increase of the previous year. 

A. doubling the increase of

B. doubling that of the increase in

C. double as much as the increase of

D. twice as many as the increase in

E. twice as many as the increase of

increase在这里是可数还是不可数？另，结尾处in与of哪个更合适？

我一碰上比较题就错，真是欲哭无泪了！