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 am hesitating between 4 options to answer the following question, which option should I choose?
Question: Why are coal, oil, and natural gas called fossil fuels?
Possibilities:
- 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.

They formed from the remains of prehistoric plants and animals.