When operating in a fire building with limited visibility, which statement is true?

In a fire building with limited visibility, crawling is indeed the safest option because it helps firefighters stay below the layers of hot gases that tend to accumulate closer to the ceiling. Hot gases and smoke can rise rapidly, creating a hazardous environment at higher levels. By staying low, firefighters reduce their exposure to these dangerous conditions, allowing them to navigate the space more safely and effectively. This technique is critical in maintaining both visibility and safety, as it keeps firefighters in a cooler layer of air where their risk of inhalation injury is diminished.

While other tactics, such as running or using flashlights, may have their own benefits in certain situations, they do not address the critical factor of thermal safety and the need to navigate more effectively in conditions of poor visibility. Walking may also seem safe but could lead to longer exposure times to potential hazards. Thus, crawling is the most practical and protective method in these scenarios.