谁能来帮个忙

4.     Urban officials want the census to be as accurate and complete as possible for the reason that the amount of low-income people in a given area affect the distribution of about fifty billion dollars a year in federal funds.

(A) for the reason that the amount of low-income people in a given area affect

(B) for the reason because the amount of low-income people in a given area effects

(C) in that the amount of low-income people in given areas effect

(D) because the number of low-income people in a given area affects（D）

(E) because the numbers of low-income people in given areas effects

为什么选D而不选A呢，虽然我个人觉得两个都 可以

the number of +名词复数。the amount of +不可数名词