Gun control is a subject Americans have argued for a long time.
A. of which B. with which C. about which D. into which
Gun control is a subject Americans have argued for a long time.
A. of which B. with which C. about which D. into which
C
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。