Modern birds and lizards share a common ancestor that was an ectotherm. Which of the following explains the fact that lizards are also ectotherms but
birds evolved to become endotherms?
A. The difference is due to the fact that birds are more highly
evolved.
B. A recent random mutation could account for the change in birds.
C. A split occurred sometime in the past in response to different
environmental pressures.
D. Birds acquired the endothermy trait so they could improve their
own chances of survival.