Final answer:
The phrase 'could indicate' suggests that there is a possibility of deliberate action if a fire breaks out shortly after an occupant leaves, but it requires further investigation and evidence before making a definitive conclusion.
Step-by-step explanation:
If the fire breaks out shortly after an occupant leaves, it could indicate the fire was set. This option acknowledges that there is uncertainty over whether a serious fire or hazard is deliberate or accidental. The potential for extreme physical danger necessitates careful consideration of all possibilities in a fire investigation. It is important to collect evidence and analyze circumstances before concluding the cause of the fire. In the context of strategy and tactics, as stated in the provided reference, it is crucial to act preemptively ‘If it is possible to make an assault with fire from without, do not wait for it to break out within, but deliver your attack at a favorable moment’—this illustrates the importance of timely intervention.