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

Fact 2: Gasoline is made up of hydrocarbons.

Given the two facts above, answer the question "A car engine uses what to aid in combustion?" with the following options: 
- carbon dioxide
 - electricity
 - organic molecules
 - thrust
 - hydrocarbons
 - a hydraulic system
 - kinetic energy
 - fossil fuels


 

     hydrocarbons    