请教新东方section24-3

In the last ten years, the dropout rate among Black high school students fell substantially over the past decade, while the number of Blacs who attend college is more than twice what it was.

(C）has fallen substantially,while the number of Blacks attending college has more than doubled.

(E)   has fell substantially over the past decade, while the number of Blacs who  are attending college are more than double what they were

答案选E,我选C

E中错误感觉至少有这么两处： over the past decade 与In the last ten years 重复，are与number主谓不一致

大家帮忙看一下，谢谢