The pollutants which come directly in the air from sources are called primary pollutants. Primary pollutants are sometimes converted into secondary pollutants. Which of the following belongs to secondary air pollutants?

Primary pollutants are directly emitted from fossil fuels, and also factories, These includes oxides of sulphur, carbon, methane. When the primary pollutants react with other components present in the atmosphere, secondary pollutants are formed. Smog, Peroxyacetyl nitrate are the examples of secondary air pollutants.