Which of the following is a secondary pollutant?

Explanation

The formation of secondary pollutants is influenced by a combination of factors, including the presence of primary pollutant emissions, meteorological conditions, sunlight, and the concentration of precursor compounds in the atmosphere. The secondary pollutants are more toxic than the primary ones. Nitrogen oxides and hydrocarbons react photochemically to produce peroxyacyl nitrates and ozone. Peroxyacyl nitrates are produced due to photochemical reactions between nitrogen oxides and unsaturated hydrocarbons.