请教prep2-139

(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 the
            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，我不明白A中each of them 怎么错了？

A和C估计 called
                the
                taste
                pore,这个东西修饰的东西不一样

如何我能知道TASTE PORE TASTE BUD,这个题目我就能 解释了

A是错在run-on sentence吧，标点符号，连词都没有

不过they或者which不会造成歧义修饰吗？

红色字体修饰歧义了，应该是修饰the
            opening 的，但A修饰的是taste bud

 prep里关于A的解释是：each在这里作代词，each
            of
            them是句子主词，后接动词has…构成完整的句子，与前面的句子之间缺少连
            词，不应用逗号。

这是什么意思啊？是说两个完整句子之间要用连词吧！each
                of
                them是主语，each
                    of
                    which就不是吗？