Tidal energy is a form of hydropower that converts the energy of tides into electricity. Tides are primarily caused by:
- Earth's rotation and solar winds
- Gravitational pull of the Moon and Sun
- Ocean currents and underwater volcanoes
- Thermal expansion of ocean water
Answer: Gravitational pull of the Moon and Sun
Tides are generated by the gravitational interaction between the Earth, Moon, and Sun, with the Moon having the dominant effect.