Evolution: Mutation and Selection
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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.

i think the answer is a.keratin is the pigment responsible for skin color.

i think the answer would be a. after sentence 14! i hope i at least a little

answer diabetes mellitus;