Which one of the following statements about air pollution is NOT correct?
OA. Sulfur dioxide and particulate matter air pollutants can both contribute to human respiratory problems.
OB. Wildfires, volcanic eruptions, and coal-fired power plants are all sources of particulate matter air pollutants.
O c. Volatile organic compounds (VOCs) and nitrogen oxides (NOx) air pollutants are a problem because they can lead to the formation of harmful photochemical smog.
OD. Vehicle emissions are the main and largest source of sulfur dioxide air pollution.