咨询prep一道sc题，请高手解答一下

The Iroquois organized their kinship groupsinto matriarchal clans, of which members traced their descent from acommon female ancestor

A.       of which members

B.       with members who

C.       members of whom

D.       whose members

E.        of members who

答案选的d，请问为什么不选C呢？请高手帮帮忙解答一下