Which of the following best defines animals in the class Aves? (i.e., which definition includes all birds and excludes all other animals, past and present?)
A) Vertebrates with a closed, double-loop circulatory system
B) Feathered anapsids
C) Endothermic feathered amniotes
D) Ectothermic tetrapods possessing feathers and lacking teeth
E) Amniotes that can fly
