You are presented with the question "what does a renewable, economical source of electricity require?" and the following answer choices: 
- damming a river
 - power stations
 - freezing h2o
 - electricity
 - burning fossil fuels
 - hydrogen and oxygen
 - sunlight
 - nuclear meltdowns

Now knowing that hydropower requires damming a river and hydropower is a renewable, economical source of electricity, choose the best answer.


 

 damming a river        