Fact 1: Mammals conserve body heat with their hair or fur.

Fact 2: Body heat is trapped in the haircoat.

Given the two facts above, answer the question "What do mammals use to conserve heat?" with the following options: 
- energy
 - Energy.
 - fur and fat
 - blood
 - haircoat
 - food
 - body water
 - tail


 

     haircoat    