Which of the Following Best Describes the Relationship Between Primary

Which of the following best describes the relationship between primary and secondary ambient air quality standards?

A) If the primary standards are met within three years of creation of a state implementation plan, then the secondary standards need not be met.
B) Both the primary and secondary standards must be met within five years of their creation.
C) The primary standards must be met within three years of the creation of a state implementation plan, and the secondary standards must be met within a reasonable time.
D) The primary standards must be met within a year of their creation, and the secondary standards must be met as soon as economically feasible.