Who is the man ____ is reading a book under the tree

题目

Who is the man ____ is reading a book under the tree
A.that B.whose C.which D.what
为什么选A不选C,请详解,

答案

A
先行词是人the man,而which 只能指事物
that 既可以指人也可以指物
who 只能指人