Distinguish between Ambient air vs tracheal air vs alveolar air.

a) Air surrounding the body; air in the trachea; air in the alveoli
b) Air in the atmosphere; air in the lungs' tubes; air in the lung's air sacs
c) Air inhaled during breathing; air in the windpipe; air in the lung's tiny air sacs
d) Air inside buildings; air in the throat; air in the lung's large air sacs