27. The spreading of fire as a result of heat being carried through a vessel's ventilation system, is an example of heat transfer by __________.

Convection is the correct answer because the fire's spread is facilitated by hot air and gases moving through the ventilation system. Convection involves heat transfer via the movement of a fluid, unlike conduction which requires direct contact, radiation which uses electromagnetic waves, or windage which describes airflow effects, not a heat transfer mechanism.