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

Multiple Choice

Although hydroelectric dams generate electricity without directly producing greenhouse gases,they ________.

A) contribute only about 5% of global electricity production
B) produce as much other air pollutants as coal-fired power plants
C) are short-lived structures that have to be rebuilt about every 20 years
D) eliminate wildlife habitats and affect the temperature of waterways