Fact 1: Acar engine usually converts gasoline into motion and heat through combustion.

Fact 2: Gasoline vapors are highly combustible.

Given the two facts above, answer the question "Car engines convert highly combustible vapors into what?" with the following options: 
- Energy.
 - tires
 - passengers
 - motion
 - movement
 - heat
 - wheels
 - energy


 

    motion     