Correct Answer: flow of water

Solution : The correct option is flow of water.

The flow of water generates motion in turbines in a hydel (hydroelectric) power station. Pipes carry water from a river or reservoir to the turbines. When high-pressure water meets the turbine blades, they revolve. This mechanical action is subsequently converted into electrical energy by driving a generator. Because the flow of water drives the whole process, hydropower plants are an efficient and renewable method of energy generation.