Hydropower requires damming a river.
Many dams along rivers and creeks help prevent floods.
Hydropower requires helping to prevent floods.
Hydropower requires what?
[A] a hydraulic system
[B] increases a body's strength
[C] helping to prevent floods
[D] Electric generators
[E] flow of electrons
[F] energy of moving objects
[G] power stations
[H] fissures of hot, acidic water