Animals with a complex body plan can maintain homeostasis in a changing environment by using all of the following except

A)sensory organs that provide information about the animal's environment.
B)internal digestive organs that break down food gradually.
C)an external skeleton that provides protection against predators.
D)a gastrovascular cavity that opens directly to the external environment.
E)filtration system that can change the composition of the interstitial and circulatory fluid.