Which Statement Describes the Most Likely Reason That a Fish

Which statement describes the most likely reason that a fish associated with a cleaner fish like Labroides dimidiatus does not eat the cleaner fish, even when the cleaner fish is in its mouth?

A) The fish is being altruistic.
B) The benefit from parasite removal is greater than that from eating the cleaner fish.
C) The cleaner fish contains noxious secondary compounds that harm other fish.
D) The cleaner fish emits a chemical that makes the other fish more docile.