Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Fossil fuels provide most of the energy used worldwide. Richer nations use far more energy resources, especially fossil fuels, than poorer nations do. There are several ways that people can conserve energy in their daily lives.


Question: What fuels provide most of the energy used worldwide?
fossil
Fossil fuels.