Hydropower requires damming a river, and hydropower is a renewable, economical source of electricity. Given these facts, what does a renewable, economical source of electricity require among the following options:
- damming a river
 - power stations
 - freezing h2o
 - electricity
 - burning fossil fuels
 - hydrogen and oxygen
 - sunlight
 - nuclear meltdowns


 

 damming a river        