In the fourth stage of a fire, which of the following statements is true?

In the fourth stage of a fire, known as the fully developed stage, the intensity of the fire has reached its peak, leading to extreme temperatures and extensive damage. At this point in the fire process, non-flaming combustibles can indeed still ignite. This means that materials not currently burning can become involved in the fire, contributing further to its spread.

Understanding that non-flaming combustibles have the potential to ignite is crucial for fire safety, as it indicates that even if there are no visible flames, the risk of fire continuation or resurgence remains significant. This is a key consideration in firefighting strategies and safety protocols, as it demonstrates the need for thorough extinguishment and assessment of all materials involved.

In contrast, the idea that fuel or oxygen is increasing doesn't accurately reflect the conditions of a fire fully developed stage, as the fire has exhausted much of the available oxygen. The danger is far from eliminated during this stage, and fire suppression measures may not be as effective due to the severity of the fire. Thus, the identification of the potential for non-flaming combustibles to ignite highlights an important aspect of fire dynamics and safety.