The book I am reading is ___ I borrowed from the library,

问题描述:

The book I am reading is ___ I borrowed from the library,
A,that B,the one C,which D,whom
答案是选B,可我就是弄不明白,that 不是等于the one 都是特指呀?

The book I am reading is the one(that) I borrowed from the library.
这里其实还省略了一个that,前面不可能还用that,the one特指就是那一本.