In the past few years he has collected a lot of ancient coins date back to the Ming and

问题补充：

In the past few years, he has collected a lot of ancient coins, date back to the Ming and Qing Dynasties.

A. most of them

B. most of that

C. most of which

D. most of those

答案：

A. most of them

B. most of that

(答案→)C. most of which

D. most of those

解析：考查非限定性定语从句关系代词.that只能用于限定性定语从句中,them和those不能用作定语从句引导词,当指物的引导词前有介词时,引导词只能用which,故选C.