Fact 1: Friction causes the speed of an object to decrease.

Fact 2: After applying the brakes firmly and slowing to the desired speed get off the brakes.

Given the two facts above, answer the question "What causes friction?" with the following options: 
- chemicals
 - Energy.
 - energy
 - wind
 - driving
 - brakes
 - heat
 - nerves


 

      brakes   