Which of the following best describes a passive barrier?

• A. Light, movable barrier
• B. Physical barrier that is temporary
• C. Passive barrier
• D. Electronic barrier

Answer: (C)

In security design, a passive barrier is something that provides protection without using power, moving parts, or electronic systems. It relies on its physical presence—like mass, material, or fixed geometry—to block or delay access, operating without any input or control.

The best description is the one that states a passive barrier because it names the concept directly and aligns with this energy-free, non-operational nature. The other options imply barriers that involve movement, power, or electronics—features that make them active or energized rather than passive. For example, a barrier that uses light or can be moved suggests an active or adjustable device, a temporary barrier isn’t defined by being energy-free, and an electronic barrier depends on power and sensors to function. Classic examples of passive barriers include solid walls, fixed fences, or unmovable bollards that deter and slow intruders by their mere presence.