D) Some kind of exoskeleton, or hard outer covering
Explanation:
Ecdysozoa is a clade of animals that gathers arthropods, nematodes and seven other phyla. These organisms have a type of exoskeleton, or hard outer lining that limits the growth of these animals. At some point in the life of these animals, the "exoskeleton" becomes tight and forces these animals to form a new exoskeleton in order to grow. The process of moving from one exoskeleton to another is called ecdysis and also happens in insects.
