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

Fact 2: If Arctic foxes are in too cool weather, they warm up by their thick fur.

Given the two facts above, answer the question "how do foxes warm up?" with the following options: 
- ligt
 - coat
 - fur
 - skin
 - two
 - water
 - fats
 - air


 

   fur      