Fact 1: Mammals generate heat mainly by keeping their metabolic rate high.

Fact 2: Gray Squirrel Management Tree squirrels are common Alabama mammals.

Given the two facts above, answer the question "What generate heat mainly by keeping their metabolic rate high?" with the following options: 
- elephants
 - fur seals
 - bacteria
 - alpacas
 - tree squirrels
 - animals
 - batteries
 - the Sun


 

     tree squirrels    