一道by的语法题

Since 1965 there are four times as many Black college students enrolled, and the one million Black people in college today represent 11 percent of all college students.

（A） Since 1965 there are four times as many Black college students enrolled
（B） The enrollment of Black college students was only one fourth in l 965

（C）The enrollment of Black college students has increased four times from l 965 on

（D）Quadrupling since l965， there are now four times as many Black college students enrolled

（E）The enrollment of Black college students has quadrupled since 1965

BY提到C项 increased four times可用quadruple代替，我觉得这里错误应该是改变原意。increased four times是否应该是five times?是不能用quadruple代替的。这样理解是否正确？

还有，BY提到there be something done永远错，这里的something指代的是four times as many Black college students?

个人意见：

似乎没有increased four times这种用法，表达增加了四倍(即原来的五倍）increase by four times；quadruple则表示增加到四倍（即增加了三倍）；本题原本想表达的意思为增加到四倍，因为用的是 four times as many ( as)；故用quadruple不改变原意。