Gun control is a subject Americans have argued for a long time.
A. of which
B. with which
C. about which
D. into which
网友回答
A. of which
B. with which
(答案→)C. about which
D. into which
解析：考查定语从句，先行词是Gun control，指物，关系词在从句中做介词的宾语，介词前置，介词与从句动词构成搭配argue about sth，选C。