Sentence Correction

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


Can anyone explain the usage of Unlike and like here. I know unlike should follow parallelism.
But do the nouns after the unlike and other comparing noun need to agree in number?

I don't believe that is happening here...Unlike other arachnids (Plural)......the scorpion (Singular)