The correct answer is Nitrogen Dioxide, Ozone, and peroxyacetyl nitrate in the presence of sunlight. * Nitrogen Dioxide: Released mainly from vehicle exhaust and industrial emissions. * Sunlight: Sunlight's energy initiates the chemical reactions that form smog. * Volatile Organic Compounds: These are released from gasoline, paints, solvents, and other sources. They react with NO2 in the presence of sunlight. * Ozone: Ground-level ozone is a major component of photochemical smog, created by the reactions between NO2 and VOCs. * Peroxyacetyl Nitrate (PAN): PAN is another harmful component of smog, formed in the same reactions. The simplified process: Sunlight triggers reactions between Nitrogen Dioxide and VOCs, leading to the formation of ozone, PAN, and other noxious components of photochemical smog.