In paragraph 5, the author mentions the atmospheric pollution and waste products for fossil fuel and nuclear power

A To introduce the discussion of pollution caused by geothermal energy development and production

B To contrast pollution caused by fossil fuels and nuclear power with pollution caused by geothermal production 

C To argue that geothermal production does not cause pollution like other sources of energy do

D To discourage the use of raw materials and chemicals in the production of energy because of pollution