What type of air pollution is formed when pollutants undergo reactions with sunlight?

The correct answer is secondary pollution because it refers to pollutants that are not directly emitted into the air but instead form through chemical reactions in the atmosphere. Specifically, secondary pollutants are often created when primary pollutants—such as volatile organic compounds (VOCs) or nitrogen oxides—react with sunlight and other atmospheric constituents like ozone. One of the most well-known examples of secondary pollution is ground-level ozone, which is created when these primary pollutants undergo photochemical reactions in the presence of sunlight.

In contrast, primary pollution consists of substances that are released directly into the air from various sources, such as power plants, vehicles, and industrial processes, without undergoing any transformation. Aerosol pollution relates specifically to tiny solid or liquid particles suspended in the air, which can originate from both primary and secondary sources but does not specifically highlight the reactive process with sunlight. Conventional pollution is a broader term that doesn't specifically define the chemical reactions involved in secondary pollution.