Which statement best describes a smoke detector's primary function?

• A. It Detects Carbon Dioxide Levels
• B. It Detects Heat on Contact
• C. It Detects Fires in Early Stages and Requires Air Flow
• D. It Detects Humidity Levels

Answer: (C)

Smoke detectors are designed to sense tiny particles produced by combustion in the air so they can warn you early about a fire. The best description is that they detect fires in their early stages and rely on air flow to bring smoke into the sensing chamber. Smoke travels through the room and into the detector, which continuously samples the air to catch signs of a developing fire before flames become intense. This early smoke sensing is what makes these devices effective for alerting occupants quickly.

Other options point to detectors that aren’t focused on smoke detection: measuring carbon dioxide levels, humidity, or heat on contact. Those devices serve different safety or monitoring roles and wouldn’t provide the same early warning for a fire as a smoke detector.