What does positive pressurization pertaining to ventilation mean?

A.
When a door opens, the air comes in.

B.
When a fire takes place, the power supply is disabled.

C.
When a fire takes place, the smoke is diverted to one room.

D.
When a door opens, the air goes out.

Explanation:
Positive pressurization means that when an employee opens a door, the
air goes out and outside air does not come in. If a facility was on fire and the
doors were opened, positive pressure would cause the smoke to go out instead of
being pushed back into the building.