Which substance is NOT a fossil fuel?

• A. Coal
• B. Natural gas
• C. Oil
• D. Wood

Answer: (D)

Wood is not classified as a fossil fuel because it is a renewable resource that comes from living trees and plants. Unlike fossil fuels, which are formed from the decomposed remains of ancient organisms over millions of years under specific geological conditions, wood is produced through the natural growth process of trees. It can be replanted and replenished, making it a sustainable option for energy and materials, as long as it is sourced responsibly.

Fossil fuels, on the other hand, include substances like coal, natural gas, and oil. These resources are derived from organic matter that has undergone significant transformation due to heat and pressure in the Earth's crust over extensive time periods. Each of these fossil fuels has a finite supply, which contributes to concerns about environmental impacts and future availability as they contribute to greenhouse gas emissions when burned.