What is the maximum concentration of a material that a person can be exposed to over a 40-hour workweek with no ill effects?

The EMT understands adequate breathing when he states:

A) "If the respiratory rate is between 10 and 20, the breathing is most likely adequate." B) "If the patient is breathing faster than 22 times a minute, it is inadequate." C) "Normal and adequate breathing is specific to the patient and is determined by assessment." D) "If the rate is between 10 and 20, with an intact airway and clear breath sounds, it is adequate."

Carrier molecules help move substances from an area of low concentration to an area of high concentration by 

A. diffusion. B. osmosis. C. filtration. D. active transport.