Heat and pressure change the remains of prehistoric living things into natural gas, and heat and pressure cause a rock to metamorphize. Given these facts, what can change the remains of prehistoric living things into natural gas among the following options:
- rock metamorphizing
 - a hydraulic system
 - Time and energy
 - the ground shaking
 - Temperature
 - one celled organisms
 - chemical reaction
 - flow of electrons


 

 rock metamorphizing        