请教大全896 谢谢各位~

896.
            Unlike other arachnids, which have their nerve cells evenly distributed along their bodies, the scorpion’s nerve cells are clustered in its head, like a mammal’s.

(A) bodies, the scorpion’s nerve cells are clustered in its head, like a mammal’s

(B) bodies, the scorpion’s head had a cluster of nerve cells, as a mammal does

(C) body, the scorpion has a cluster of nerve cells in its head, as a mammal does

(D) body, nerve cells are clustered in the scorpion’s head, like a mammal’s（C）

(E) body, a cluster of nerve cells is in the scorpion’s head, like a mammal’s

为什么是用their body,而不用their bodies? 以前有人问过这个问题，但是好像没解释清楚.还是不明白为什么their 后能跟单数，有什么例句可以说明吗？光从句意上这样理解有些牵强阿。谢谢各位喽!

自己顶下~