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

Fact 2: Pugs are mammals and mammals shed.

Given the two facts above, answer the question "what generates heat mainly by keeping their metabolic rate high?" with the following options: 
- humans
 - Birds
 - bats
 - cats
 - voles
 - pugs
 - pigs
 - shrews


 

      pugs   