the population of the city_ works?

题目

the population of the city_ works?
-_of the population of the city_ works?
-About 60 percent
A.What,is
B.What,are
C.How much,is
D.How much,are
选了C,想问问为什么捏?

答案

主语是后面的works,不过怎感觉这拼错了,应该是workers的吧,所以应该是复数,换成陈述句就是About 60 percent of the population are workers.把这些当成复数来说的.应该是这样