Which of the following is NOT a fossil fuel?

Fossil fuels are natural resources formed from the decomposed remains of ancient plants and animals, which have been subjected to heat and pressure over millions of years. Coal, natural gas, and oil all fall into this category as they are derived from organic matter that has been transformed over geological time.

Wind, on the other hand, is not a fossil fuel. It is a renewable energy source generated by the movement of air caused by uneven heating of the Earth's surface by the sun. Unlike fossil fuels, wind energy does not involve burning organic materials or releasing carbon dioxide and other pollutants into the atmosphere, making it a cleaner alternative for generating electricity. Therefore, identifying wind as not being a fossil fuel is accurate, as it operates on entirely different principles of energy generation compared to coal, natural gas, and oil.