Which of the following statements about skeletons is NOT true?

A)The skeleton of a vertebrate is an endoskeleton.
B)The skeleton of an arthropod is an exoskeleton.
C)The skeleton of a clam is an exoskeleton.
D)All exoskeletons must be shed as the animal grows.
E)An earthworm has a fluid-filled cavity that acts as a hydrostatic skeleton.