Which of the following is an important concept in Darwin's theory of evolution by natural selection? A) descent with modification, B) homologous molecules, C) processes that change the surface of Earth, D) the tendency toward perfection

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.