Correct Response: D. Acid rain is caused by sulfur dioxide and/or nitrogen oxides reacting in the atmosphere to produce acidic compounds. The major source of the sulfur dioxide and nitrogen oxides is the burning of fossil fuels by power plants and manufacturing industries. Although woodstoves (A) and solid waste incinerators (C) emit sulfur dioxide and nitrogen oxides that can contribute to acid rain formation, the amount of these gasses produced by woodstoves and incinerators is less than the amount produced by power plants and factories. Even though the use of radiation-emitting substances in manufacturing (B) causes its own health and environmental concerns, it does not significantly contribute to the gasses that cause acid rain.