Question

how has the epa improved air quality over the last 30 years?
○ by monitoring pollutants and passing regulations to reduce air pollution
○ by decreasing soil erosion and dust storms
○ by building marine refuges to help protect marine life and reduce air pollution
○ by decreasing of fossil fuel use in motor vehicles and industry

Explanation:

The EPA's core strategies for improving air quality involve systematic tracking of pollutants and implementing regulatory measures to limit emissions. The other options are either unrelated to the EPA's primary air quality work (marine refuges, soil erosion) or describe outcomes enabled by the EPA's regulatory actions rather than the agency's direct, overarching approach.

Answer:

by monitoring pollutants and passing regulations to reduce air pollution