What can increase the risk of rapid fire spread?

The choice of a higher fire load is correct because it directly correlates with the potential for rapid fire spread. Fire load refers to the total amount of combustible material present in a given area, including furnishings, textiles, and structural elements. When the fire load is high, there is more fuel available for the fire, which can significantly enhance both the intensity and the speed at which the fire spreads. This is particularly critical in a firefighting scenario, as a greater quantity of combustible materials can lead to a quicker and more intense fire, making it more challenging to control and extinguish.

In contrast, a well-sealed building can actually help contain a fire by limiting oxygen supply, which is essential for combustion. Lower-than-average humidity levels can increase fire behavior but aren't solely responsible for rapid fire spread without considering the fuel available. A thorough pre-fire plan is essential for fire prevention and mitigation, but it does not inherently increase the risk of fire spread; rather, it is a proactive measure designed to address and manage risks effectively. Thus, understanding fire load helps in evaluating how quickly a fire can advance within a given environment.