Which Is an Adaptation Used by Endotherms, but Not by Ectotherms

Multiple Choice

Which is an adaptation used by endotherms, but not by ectotherms, to produce an increase in body temperature?

A) Repeated contraction of flight muscles without movement
B) Cluster or huddling behavior
C) Decreased surface-to-surface contact with a cold environment
D) Circulatory changes to maintain core or internal temperatures greater than the animal's peripheral temperatures
E) Metabolism of brown fat