Fact 1: Feathers help birds fly and provide insulation.

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

Given the two facts above, answer the question "Feathers help what kind of animals fly and provide insulation?" with the following options: 
- preventing heat transfer
 - dragons
 - passenger pigeons
 - butterflies
 - animals in the class Aves
 - airplanes
 - it protects them
 - retaining heat


 

     animals in the class Aves    