The Clean Air Act was enacted in 1970.
Here's why:
1. The Clean Air Act is a federal law in the United States that aims to control air pollution on a national level.
2. It was first enacted in 1970 and has since been amended several times to strengthen regulations on emissions that contribute to air pollution.
3. The Act has provisions to regulate emissions from both stationary and mobile sources such as factories, power plants, and vehicles.
4. By setting standards for air quality and regulating emissions, the Clean Air Act helps protect public health and the environment.
Therefore, out of the options provided, 1972 is the closest to the actual year of enactment.
