When performing size-up, which question can most reliably be answered based on the time of day?

• A. Is the building occupied?
• B. Is the alarm a result of system malfunction?
• C. Was the fire intentionally set?
• D. Is the fire threatening exposures?

Answer: (A)

The key idea here is using time of day to gauge occupancy during size-up. When you arrive at a scene, knowing whether a building is likely occupied helps you estimate how many people might be inside, where they might be located, and what kind of search or rescue resources you’ll need. Time of day often maps to occupancy patterns—business hours tend to mean more people inside, while late at night or during off-hours usually means fewer occupants. That makes the question about whether the building is occupied the one you can answer most reliably just from the time of day.

The other questions require information you can’t reliably infer from time alone. Whether the alarm is a system malfunction depends on alarm indicators or system status; whether the fire was intentionally set requires evidence or patterns beyond what time reveals; whether the fire is threatening exposures depends on the fire’s location, spread, and surrounding structures. Those factors aren’t determined simply by the hour.