Over a three-year period, a city’s environmental protection department measure the particulate matter (PM2.5) in a ten-square-mile area around one of the city’s coal-fired power plants. The annual mean level of PM2.5 was 20.0 micrograms/m3 over the three-year study period. The National Ambient Air Quality Standards (NAAQS) for PM2.5 is an annual mean level of 12.0 micrograms/m3, averaged over three years. The city instructs the manager of the power plant to propose a plan to aid the city in meeting the NAAQS for PM2.5 in the area around the power plant over the next ten years. Which of the following would be the most effective plan for the manager to propose to the city?
Responses

Install catalytic converters at the plant.
Install catalytic converters at the plant.

Burn lignite coal instead of bituminous coal at the plant.
Burn lignite coal instead of bituminous coal at the plant.

Install vapor recovery nozzles at the plant.
Install vapor recovery nozzles at the plant.

Install electrostatic precipitators at the plant.