Which of the Following Statements Is True of Air Pollution

Which of the following statements is true of air pollution?

A) Air pollution occurs when more pollutants are emitted into the atmosphere than can be safely absorbed and diluted by natural processes.
B) A majority of the people in the U.S. breathe unsafe air for at least part of the year.
C) Air pollution caused by particulate matter is responsible for fewer than 600 premature or unnecessary deaths annually.
D) The EPA has identified hundreds of "criteria" pollutants, relatively common harmful substances that serve as indicators of overall levels of air pollution.