Which of the following is not a common zone type used in security systems?

• A. Option zone
• B. Perimeter zone
• C. Interior zone
• D. Motion zone

Answer: (A)

Zone typology in security systems classifies detectors by the protection role they serve, such as perimeter zones that cover doors and windows, interior zones that monitor inside spaces, and motion zones that detect movement within a protected area. An “Option zone” isn’t a recognized category in most alarm panels or design standards; it isn’t tied to a specific protection purpose, so it wouldn’t be used as a standard zone type. That’s why it’s not a common zone type. The other options—perimeter, interior, and motion—are all widely used categories that correspond to established protection strategies: guarding entry points, monitoring interior areas, and detecting intruders through movement.