Which of the Following Statements About the U

Which of the following statements about the U.S. Clean Air Act is true?

A) The Clean Air Act of 1970 focused on about 200 air pollutants.
B) The most dramatic improvement in air quality has been a reduction of lead in the atmosphere.
C) Sulfur dioxide emissions since 1970 have been reduced by over 90%.
D) The Clean Air Act was passed in 1970, but has not been updated since then.
E) Urban areas have done the best job of meeting the standards for clean air.