Which was a requirement of the clean air act? car manufacturers had to make smaller cars. cleaner-burning gas had to be used in cars. drivers had to drive shorter distances. car manufacturers had to make electric cars.

Cleaner-burning gas had to be used in cars

The Clean Air Act is a United States federal law designed to control air pollution on a national level. It is one of the United States' first and most influential modern environmental laws, and one of the most comprehensive air quality laws in the world.

The law is designed to reduce acid rain and improve public health by dramatically reducing emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx).

B on ED

Explanation:

were they embroiderers?