Which of the following describes the characteristics of passive barrier systems?

• A. Have substantial bulk or mass.
• B. Are permanently installed or require heavy equipment to move.
• C. Both A and B.
• D. None of the above.

Answer: (C)

The key idea is that passive barrier systems provide protection through physical presence and immovability rather than active action. They rely on substantial mass to resist force and on being fixed in place or very difficult to move, so they don't require power, sensors, or human intervention to work. That's why describing them as having both a lot of bulk and a permanent installation (or requiring heavy equipment to move) fits best—mass gives resistance, and fixed positioning ensures they stay in place under threat. If you only had bulk without permanence, the barrier could be relocated or bypassed; if you only had permanence without sufficient mass, it might be easier to defeat with enough force.