Describe fossil fuels.

• A. They are renewable resources formed by photosynthesis.
• B. They are nonrenewable resources formed from decayed organisms over millions of years.
• C. They are produced by hydroelectric dams.
• D. They are synthesized in laboratories.

Answer: (B)

Fossil fuels are nonrenewable energy resources formed from the remains of ancient plants and microorganisms that have been buried, heated, and compressed for millions of years. The energy they contain originally came from sunlight captured by those organisms through photosynthesis, but the transformation into coal, oil, or natural gas requires long-term geological processes that change the organic matter over vast timescales. Because this formation takes geologic ages, fossil fuels cannot be replenished on human time scales, making them finite. They are not produced by hydroelectric dams or synthesized in laboratories, so the description that best fits is that they are nonrenewable resources formed from decayed organisms over millions of years.