Fact 1: Thick fur can be used for keeping warm.

Fact 2: Carpet beetle larvae feed on the keratin and chitin commonly found in wool, fur, or feathers.

Given the two facts above, answer the question "What can be used for keeping warm?" with the following options: 
- keratin
 - vacuum
 - four limbs
 - energy
 - cold
 - engines
 - magic
 - heat


 

 keratin        