You are presented with the question "Hydropower requires what?" and the following answer choices: 
- 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

Now knowing that hydropower requires damming a river and many dams along rivers and creeks help prevent floods, choose the best answer.


 

   helping to prevent floods      