Although Hydroelectric Dams Generate Electricity Without Producing Greenhouse Gases,they __________________

Multiple Choice

Although hydroelectric dams generate electricity without producing greenhouse gases,they __________________

A) contribute only about 5% of the electrical power throughout the world
B) still produce more greenhouse gases per unit of electricity produced than coal power plants
C) can harm aquatic organisms downstream by affecting water temperature
D) cannot provide a consistent supply of electricity during times of naturally low river flow
E) are short -lived structures that have to be rebuilt about every 20 years