Fact 1: Hydropower requires damming a river.

Fact 2: Many dams along rivers and creeks help prevent floods.

Given the two facts above, answer the question "Hydropower requires what?" with the following options: 
- a hydraulic system
 - increases a body's strength
 - helping to prevent floods
 - Electric generators
 - flow of electrons
 - energy of moving objects
 - power stations
 - fissures of hot, acidic water


 

   helping to prevent floods      