only coal. only natural gas. oil and coal. oil and natural gas.
I gave my students this multiple choice question: Fossil fuels were made from specific kinds of ancient organisms. The fossilized remains of tiny ocean organisms formed

Only one answer is correct among these 4 choices:
- only coal.
- only natural gas.
- oil and coal.
- oil and natural gas.

Could you tell me which one is correct?

oil and natural gas.