The correct answer is C. Peroxyacetyl nitrate (PAN).
PAN is a powerful eye irritant present in smog. It is a secondary pollutant, meaning that it is formed in the atmosphere by the reaction of primary pollutants, such as nitrogen oxides and volatile organic compounds. PAN is a colorless gas with a pungent odor. It is highly reactive and can damage plants, animals, and humans.
Nitric oxide (NO) is a colorless, odorless gas that is produced by the combustion of fossil fuels. It is also a major component of smog. NO is not directly harmful to humans, but it can react with other pollutants to form harmful compounds, such as PAN.
Sulphur dioxide (SO2) is a colorless, odorless gas that is produced by the burning of fossil fuels that contain sulfur. It is also a major component of smog. SO2 can irritate the eyes, nose, and throat. It can also cause respiratory problems, such as asthma and bronchitis.
Carbon dioxide (CO2) is a colorless, odorless gas that is produced by the burning of fossil fuels. It is also a natural component of the atmosphere. CO2 is not directly harmful to humans, but it can contribute to climate change.
In conclusion, the correct answer is C. Peroxyacetyl nitrate (PAN). PAN is a powerful eye irritant present in smog. It is a secondary pollutant, meaning that it is formed in the atmosphere by the reaction of primary pollutants, such as nitrogen oxides and volatile organic compounds. PAN is a colorless gas with a pungent odor. It is highly reactive and can damage plants, animals, and humans.