Answer:
B). It requires air pollution controls to be installed on motor vehicles.
Explanation:
The Clean Air Act primarily intended to set the parameters or standards for ambient air quality in the United States and plans associated with implementation of these standards.
As per the question, option B i.e. 'It requires air pollution controls to be installed on motor vehicles' that would assist in maintaining the air quality standards and keep the air safe for the citizens. This installation of air pollution control measures on the motor vehicles assisted in controlling the dangerously exceeding pollution in the state and reform the quality of air. Therefore, option B is the correct answer.
