有一道英语单选,并大家帮我看看并解析一下,

题目

有一道英语单选,并大家帮我看看并解析一下,
about $5000 a year is spent on each private school pupil,____the amount spent on state school pupils.
A.as twice as B.twice more as
C.more than twice D.more twice than

答案

c