Solution

When the solar radiation reacts with airborne pollutants like nitrogen oxides and volatile organic compounds, the product compounds called as primary pollutants, are often introduced into the atmosphere through automobile emissions and industrial processes. Ultraviolet light can split nitrogen dioxide into nitric oxide and monatomic oxygen, this monatomic oxygen reacts with oxygen gas to form ozone. Products like ozone, aldehydes, and peroxyacetyl nitrates are called as secondary pollutants. The mixture of these primary and secondary pollutants forms photochemical smog. Thus, the correct answer is option A.