Some Fish Give Off a Chemical When Injured That Signals

Some fish give off a chemical when injured that signals to other fish that a predator is nearby.The chemical causes the uninjured fish to group together in a tight formation,move to the bottom of the water and cease movement to make it less likely that they will be preyed upon.

A) This is communication using a chemical signal.
B) This is a futile attempt by the fish to survive.
C) An unnecessary action since the predator already has killed its prey.
D) This is a visual signal to the predator that they are prey items.
E) This behavior will only work one time.