Fact 1: An animal requires energy to move.

Fact 2: When an animal moves, it burns energy.

Given the two facts above, answer the question "What allows for movement in animals?" with the following options: 
- the digestive system
 - an external framework
 - energizing crystals
 - Veins and arteries.
 - spinning wheels
 - burning energy
 - arteries
 - changing tires


 

      burning energy   