Fact 1: Birds are endothermic tetrapod vertebrates.

Fact 2: Class Aves is for the birds, literally.

Given the two facts above, answer the question "What kind of animal would be an endothermic tetrapod vertebrate?" with the following options: 
- animals in the class aves
 - barks and snarls
 - passenger pigeons
 - Something that is self-aware
 - Generating heat
 - retaining heat
 - absorb light energy
 - it keeps an organism warm


 

 animals in the class aves        