The right option is; C. tides
Tides is the ocean movement that power plants use to produce usable energy.
Tides are the periodic change (rise and fall) of sea levels, particularly caused by the gravitational influence of the sun and the moon and the earth’s rotation. Power plants converts the kinetic energy derived from tides into usable form of energy particularly electricity. The tidal energy is considered as a renewable energy resource.The higher the tidal variation and tidal current velocities, the higher the ability of a site to generate tidal electricity.