Fact 1: Heat and pressure change the remains of prehistoric living things into natural gas.

Fact 2: Fossils are the remains of prehistoric life.

Given the two facts above, answer the question "What two things turn fossils to natural gas?" with the following options: 
- heat and cold
 - heat and fuel
 - hydrogen and oxygen
 - heat and pressure
 - pressure and time
 - scarce resources
 - kinetic energy
 - chemical changes


 

    heat and pressure     