You are presented with the question "What is formed from layers of sediment covering the remains of organisms over time?" and the following answer choices: 
- metal
 - cold
 - rings
 - coral reef
 - sea urchins
 - natural gas
 - exoskeleton
 - shells

Now knowing that fossils are formed when layers of sediment cover the remains of organisms over time and natural gas is a fossil fuel, choose the best answer.


 

      natural gas   