One Provision of the Clean Air Act of 1970 Required

One provision of the Clean Air Act of 1970 required cities where smog was still a problem, despite emission controls placed on new cars, to impose rules restricting the public's use of cars. This provision failed because

A) the Environmental Protection Agency (EPA) adopted an overly zealous command-and-control strategy.
B) public opposition was too great.
C) the provision was ruled unconstitutional.
D) powerful client groups worked to defeat the provision.
E) automobiles were soon viewed as having little or no impact on air pollution.