What is the key visible difference between an open fire and a confined fire?

• A. An open fire can be seen
• B. A confined fire can be seen
• C. A confined fire cannot be seen
• D. Both fires can be seen

Answer: (A)

The main idea is visibility of the flame. An open fire burns in the open, so the flames and much of the heat and light are directly visible. A fire that’s confined to a space—inside a room, compartment, or duct—tends to be hidden behind walls or doors, so you often can’t see the flames even though the fire is burning. You might instead notice signs like heat, smoke, or a glow within the enclosure. This is why the clear, practical difference is that an open fire can be seen, while a confined fire is not readily visible.