Name four renewable energy resources and explain why each one is classed as renewable.

Examples include wind, solar, hydroelectricity, tidal, wave, geothermal, and bio-fuel. They are renewable because the energy source is naturally replenished on a human timescale.

A full answer should name examples such as wind, solar, tidal, wave, hydroelectricity, geothermal energy or bio-fuel, then explain that their energy sources are naturally replenished. For instance, solar depends on radiation from the Sun, hydroelectricity links to the water cycle, tidal uses regular sea-level changes, and bio-fuel can be regrown. The explanation must not imply that renewables have no environmental impact; it only needs to justify why they are renewable rather than finite.