Which of the Following Statements Best Describes the Procedures Under

Which of the following statements best describes the procedures under the Clean Air Act?

A) The federal government sets and enforces the standards.
B) The state governments set and enforce the standards.
C) The federal government sets the standards, and the state governments enforce the standards; if the states do not adequately enforce the standards, the federal government may enforce them.
D) The state governments set the standards, and the federal government enforces the standards; if the federal government does not adequately enforce the standards, the states may enforce them.
E) Both the federal and state governments set standards, and each enforces its own standards.