You are presented with the question "Animals usually require what for survival?" and the following answer choices: 
- organic molecules
 - organic material
 - Fluctuating body temperature.
 - Ears
 - food and shelter
 - Cold blood
 - Organic compounds
 - Constant body temperature.

Now knowing that an animal usually requires a warm body temperature for survival and warm blooded animals have a constant body temperature, choose the best answer.


 

        Constant body temperature. 