再问PREP39

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

答案是C,可是C中called。。。和located。。。中间用逗号分隔，没有加连词，难道不是一个run-on 么？

插入语。。。

i am the one, named william, accepted by the school.

我明白了，从你举的例子来看，located...作为projections的后置定语，可是这样意思说得通么。。。located...到底是修饰projections 的还是修饰cells的。。。