Fact 1: Some animals' fur grows thicker for staying warm in the winter.

Fact 2: During winter, their hollow fur absorbs much heat as they sun themselves.

Given the two facts above, answer the question "hollow fur keeps animals what" with the following options: 
- fats
 - camouflaged
 - safe
 - warm
 - cooled
 - liquid
 - live
 - from drowning


 

    warm     