This is an unpleasant subject __________ we might argue for a long while.

A.in which　

B.with them

C.about which　

D.with it

答案及解析： C

此题考查带介词的定语从句。做此题要抓准两点:一是先行词是subject；二是定语从句中的谓语动词argue是不及物动词。