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

Fact 2: Friction is a Force that opposes motion.

Given the two facts above, answer the question "what causes the speed of an object to decrease" with the following options: 
- kilometers
 - kinetic energy
 - Electrical energy
 - increase h2o
 - principals of aerodynamics
 - basic building blocks of life
 - opposing motion force
 - increase oxygen


 

       opposing motion force  