In the Human Gas Exchange System

In the human gas exchange system,

A) the lungs and airways are completely collapsed after a forceful exhalation.
B) the average PO₂ concentration of air inside the lungs is always lower than that in the air outside the lungs.
C) the production of surfactant increases the effort required for inhalation.
D) the amount of air that is moved per breath during normal, at-rest breathing is termed the vital capacity.
E) O₂ and CO₂ are actively transported across the alveolar and capillary membranes.