They were once fossils. They were formed in prehistoric times. They are used to heat our homes and businesses. They formed from the remains of prehistoric plants and animals.
I gave my students this multiple choice question: Why are coal, oil, and natural gas called fossil fuels?

Only one answer is correct among these 4 choices:
- They were once fossils.
- They were formed in prehistoric times.
- They are used to heat our homes and businesses.
- They formed from the remains of prehistoric plants and animals.

Could you tell me which one is correct?

They formed from the remains of prehistoric plants and animals.