GMAT Sentence Correction (SC) | Re: Unlike other arachnids, which have their nerve cells evenly

If it is just the GMAT, It will be enough to know that the comparison is intact only in C and all others are faulty. So tick C and keep going without bothering about the accompaniments. The mention of bodies or body is just to hoodwink the candidate away from the comparison

However, if it is for the sake of knowledge, then I think both body and bodies are correct and one can cite umpteen instances to support each case.