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

Fact 2: Mammals are also warm-blooded and are covered with hair or fur.

Given the two facts above, answer the question "some animals are what for staying warm in the winter?" with the following options: 
- hot headed
 - dormant
 - coiled
 - warm-blooded
 - cold-blooded
 - When it's cold
 - chill minded
 - bullfrogs


 

    warm-blooded     