Fact 1: Hair is a fiber that is found only in mammals.

Fact 2: All mammals are warm-blooded.

Given the two facts above, answer the question "What fiber can be found only in warm-blooded animals?" with the following options: 
- teeth
 - birth marks
 - muscle
 - taste buds
 - hair
 - wool
 - sugar
 - fur


 

     hair    