Which of the following is a passive safeguard?

• A. Diking
• B. Check Valve
• C. Alarm System
• D. Interlock System

Answer: (A)

Passive safeguards are features built into a facility that reduce risk without energy input or human action. A dike serves as a fixed physical boundary designed to contain spills and prevent them from spreading to other areas. Because it works by its very presence—without sensors, alarms, or operator intervention—it fits the idea of a passive safeguard. The other options rely on detection, automatic control, or operator action to mitigate risk: alarms require someone to respond, interlocks enforce safe conditions through control systems, and a valve or other flow-control device operates as part of the process but is not a fixed site barrier like a dike.