How can carbon dioxide be considered a pollutant when it is a natural component of air?
a. carbon dioxide is considered a pollutant even though it is a natural component of air, because it is
harmful to all living organisms.
b. carbon dioxide is considered a pollutant when larger concentrations than normal are present in the
air as a result of human activity
с. carbon dioxide is considered a pollutant, because it forms harmful chemicals when mixed with other
pollutants in the air.
d. carbon dioxide cannot be considered a pollutant under any circumstances.