How is electricity generated from hydroelectric dams or ocean tides?

A) water is pumped upward and then back down
B) turbines are used to pump the water upward and generators produce the electricity
C) water piles up behind a dam or tidal barrier and flows down because of gravity
D) all of these

Hydroelectric Dams

Dams built to generate electricity by using the energy of water flowing through turbines.

Ocean Tides

The regular rise and fall of the sea level caused by the gravitational pull of the moon and sun on the Earth's oceans.

Turbines

Machines for producing continuous power in which a wheel or rotor, typically fitted with vanes, is made to revolve by a fast-moving flow of water, steam, gas, air, or other fluid.