Concept:Harmful gases and tiny particles enter the atmosphere mainly through burning of fuels, motor vehicle exhausts, and industrial or household emissions.
Explanation:When fossil oils are burned, substances such as sulphur dioxide and smoke are released into the air.
Vehicle exhausts are a major source of carbon monoxide, nitrogen oxides, and other gaseous pollutants.
Aerosols, whether from spray cans or fine droplets in the air, also contribute to air pollution.
Industrial chimneys can pollute the air, but options such as river dams, acid rain, or sewage are not direct sources of air pollutants.
Therefore, the option that best combines a common pollutant and real emission sources is the one containing sulphur dioxide, vehicle exhausts, and aerosols.
Answer:C. sulphur dioxide, vehicle exhausts, and aerosols.