PREP39,对正确答案中的独立主格有疑惑,请教!!

39. Taste buds are onion-shaped structures with between 50 and 100 taste cells, each of them has fingerlike projections poking through the opening located at the top of the taste bud called the taste pore.

A. them has fingerlike projections poking through the opening located at the top of the taste bud called the taste pore

B. them that have fingerlike projections that poke through an opening located at the top of the taste bud, which they call the taste pore

C. which has fingerlike projections poking through the opening, called the taste pore, located at the top of taste bud

D. which having fingerlike projections that poke through an opening, which is called the taste pore, located at the top of the taste bud

E. which have fingerlike projections that are poking through an opening located at the top of the taste bud called the taste pore

AB,EACH OF THEM都是独立主格, A不能加句子;那么C ,EACH OF WHICH为什么就不是独立主格结构了呢?谢谢

which引导从句啊