Leakage and Diffusion of a Gas (Such as Air or Water

Multiple Choice

Leakage and diffusion of a gas (such as air or water vapor) through a building envelope are two different mechanisms because

A) leakage occurs through holes, cracks, and openings in the envelope, while diffusion occurs through the body of envelope component or its material(s) .
B) leakage refers to water leaking through the envelope (such as rainwater or subsoil water) and diffusion refers to the passage of water vapor through the envelope.
C) diffusion does not occur through a building envelope while leakage does.
D) leakage occurs through the body of the component or material(s) of the envelope, while diffusion occurs through holes, cracks, and openings in the envelope.
E) none of the above.