169. Ventilation systems connected to a compartment in which a fire is burning are normally closed to prevent the rapid spread of the fire by which method?

Ventilation systems close to prevent fire spread via convection, which is heat transfer by the movement of hot gases or air. Conduction transfers heat through solids, radiation through electromagnetic waves, and spontaneous combustion is a fire cause, not a spread method. Ventilation moves hot air and smoke, facilitating convection and potentially spreading fire to other compartments; closing these systems limits this convective spread.