Birds differ from other reptiles in that birds ____.

A) have four limbs
B) lay amniotic eggs
C) maintain a constant body temperature
D) fertilize eggs internally
E) possess a dorsal nerve cord

Constant Body Temperature

The maintenance of a steady internal body temperature regardless of external environmental changes.

Birds

Warm-blooded vertebrates with feathers, wings, a beak, and typically the ability to fly, laying hard-shelled eggs.