EPA priority pollutants are:

• A. A huge list, but Sulfur dioxide, carbon monoxide, ozone, nitrogen dioxide, particulate matter, and lead are especially naughty
• B. Only heavy metals
• C. Only pesticides
• D. Only chlorinated solvents

Answer: (A)

Priority pollutants are a large, defined set of contaminants that the EPA targets for regulation because of their potential to cause harm. This list covers many chemical families—heavy metals, pesticides, solvents, volatile organics, and more—not just a single category. Among these, certain common air pollutants are highlighted as especially problematic due to widespread exposure and well-established health effects: sulfur dioxide, carbon monoxide, ozone, nitrogen dioxide, particulate matter, and lead. These six are tracked and regulated most rigorously, which is why they’re singled out as particularly “naughty” in study materials. So recognizing that the EPA maintains a broad roster of priority pollutants, with these six especially problematic, matches how the program actually concentrates oversight. The other options are too narrow, listing only one pollutant category rather than the full, diverse EPA priority-pollutant set.