Which phenomenon is a result of the interaction between sunlight and primary pollutants?

Photochemical smog is formed through the interaction of sunlight with primary pollutants, particularly nitrogen oxides (NOx) and volatile organic compounds (VOCs). When these primary pollutants are emitted into the atmosphere, particularly from vehicle exhaust and industrial processes, sunlight triggers a series of chemical reactions that convert these pollutants into secondary pollutants, including ozone at ground level and other harmful compounds.

This phenomenon is most prominent in urban areas with high levels of traffic and sunlight, leading to a characteristic brownish haze. In contrast to other options, such as acid rain—which primarily results from sulfur dioxide and nitrogen oxides reacting with water in the atmosphere—photochemical smog specifically relates to the role of solar energy in driving the chemical reactions that produce ozone and other secondary pollutants. Ozone depletion and climate change involve different mechanisms and do not directly arise from the interaction of sunlight with primary pollutants in this specific manner.