Money control is a subject ______they have argued for a long tim

Money control is a subject ______they have argued for a long time.
A、of which
B、for which
C、with which
D、about which
【正确答案】：D
【题目解析】：如果关系代词是介词补语，我们在选用关系代词时取决于介词的位置。介词在从句句首时，表人选whom，表物选which。Argue about表示“为……争论”。