Some sources of renewable energy are ________________.

• A. Natural gas and nuclear
• B. Coal and diesel
• C. Steam and gasoline
• D. Solar Heat, Wind, Waves and Tides

Answer: (D)

Renewable energy sources come from natural processes that replenish themselves on a human timescale, so they can be used repeatedly without running out. Solar heat, wind, waves, and tides fit this idea because they are driven by the sun and the Earth’s natural forces that are continually present, providing energy continuously with the right technology to capture it.

The other options rely on finite resources or nonrenewable processes. Natural gas, coal, diesel, and gasoline come from fossil fuels formed over millions of years and are depleted as they’re used. Nuclear energy depends on uranium, which is not replenished on practical timescales. Steam is not a source of energy itself but a condition or carrier of heat, often produced by burning fuels.