Which type of inspection must be performed in areas with high air pollution?

The correct choice focuses on emissions inspection, which is specifically designed to measure the amount of pollutants emitted by vehicles. In areas with high air pollution, there are stricter regulations and needs to monitor vehicle emissions, as these contribute significantly to poor air quality. Emissions inspections help ensure that vehicles are not releasing harmful levels of pollutants into the atmosphere, thus aiming to improve overall air quality and protect public health.

In contrast, while a safety inspection evaluates the vehicle's overall mechanical condition to ensure it operates safely, it does not specifically address the emissions produced. A mechanical inspection typically examines the functioning of various parts of the vehicle without assessing emissions, and a visual inspection may only involve examining certain elements without any testing that pertains to pollutants. Hence, emissions inspections are particularly critical in polluted areas to mitigate environmental impact.