Question

Gun control is a subject     Americans have argued for a long time. 

A．of which

B．with which

C．about which

D．into which

Answer 1

C

句意：枪支控制是美国人争论了很久的话题。由句意判断后半句是定语从句，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。