估计楼主A选项把books忘掉了,as much as 也可以,表示程度.
D是合适的
涉及到程度和数量,可以用下面两个结构：
as much （不可数名词） as
as many （可数名词复数） as
You must speak english as much as you can
You have made as many mistakes as I have