Fact 1: An animal usually requires a warm body temperature for survival.

Fact 2: Warm blooded animals have a constant body temperature.

Given the two facts above, answer the question "Animals usually require what for survival?" with the following options: 
- organic molecules
 - organic material
 - Fluctuating body temperature.
 - Ears
 - food and shelter
 - Cold blood
 - Organic compounds
 - Constant body temperature.


 

        Constant body temperature. 