Two forces cause smoke to pressurize in a building: smoke volume and:

The correct answer highlights convection heat as a vital factor influencing smoke behavior in a building during a fire. When a fire occurs, it generates not only heat but also smoke. The smoke, being a product of combustion, is heated and tends to rise due to convection currents. As the smoke rises, it creates a pressure differential; warm air is less dense than cooler air. This process results in the pressurization of smoke in specific areas of the building, as the hot smoke accumulates near the ceiling or designated higher points, potentially leading to lower visibility and increasing the risk of smoke inhalation for anyone present.

Understanding convection heat in this context is crucial, as it illustrates how temperature gradients impact the movement and concentration of smoke within a building.