Which set of laws established emissions standards for cars and factories and set minimum standards for states?

• A. Clean Air Act
• B. Environmental Protection Act
• C. Air Quality Act, 1967
• D. Air Quality Act, 1967 and various Clean Air Acts, 1960s-1990s

Answer: (D)

Emissions standards for cars and factories plus minimum standards for states come from a federal framework that sets national pollution limits and then requires states to implement plans to meet them. The Air Quality Act of 1967 began this pattern by funding and guiding state air-pollution programs. But it was the Clean Air Acts (adopted in the 1970s and expanded in later decades) that truly established concrete emissions standards for both mobile sources (cars) and stationary sources (factories) and imposed duties on states to adopt and enforce plans to reach those standards. So, including both the 1967 Air Quality Act and the later Clean Air Acts best captures the full system described. The other options don’t reflect this combined, evolving framework.