[SC悬赏令] 一道sc同位语题目求解！！

20.One automobile manufacturer has announced plans to increase the average fuel efficiency of its sport utility vehicles by 25 percent over the next five years, amounting to roughly five miles per gallon, and representing the first significant change in the fuel efficiency of any class of passenger vehicle in almost two decades.

A.amounting to roughly five miles per gallon, and representing

B.amounting to roughly five miles per gallon, and it would represent

C.an increase that would amount to roughly five miles per gallon and it would represent

D.an increase that would amount to roughly five miles per gallon and would represent

E.which is an increase amounting to roughly five miles per gallon, representing

本题答案是d

我不明白为什么不能选a呢，为什么后面的ing不能用来解释前面说的怎么个增加法呢？为什么非要用同位语来修饰呢？

求各位nn解答！超级感谢！