英语定语从句的问题

Question

there are nine planets in the solar system,----are larger than our earth

A.some of them
B.some of whom
C.some of that
D.some of which

请问选哪个选项？为什么呢？

Answer 1

D
因为是非限制性定语从句
一般都是用which

Answer 2

这个题目要是真不会做,定语从句需要从头重新学!