.——I’ve read and another book this week .——Well ,maybe ________is not how much you read but what you read that counts .A this B that C there D itwhy?

.——I’ve read and another book this week .
——Well ,maybe ________is not how much you read but what you read that counts .A this B that C there D it
why?

it在这里是个形式主语,从not开始才是真正的主语.
在4个选项里只有it是可以这么用的

因为it用来指代上文已出现过的，是特指