A water treatment plant uses specialized systems to control the balance of chemicals prior to adding them to the public water supply. The treatment plant has already isolated the system from both…

Implementing two-person control procedures is a critical administrative control for highly sensitive systems, ensuring that no single individual can perform an action without a second person's verification or approval, significantly reducing insider threat and accidental error risks.

Developing insider threat training is a good awareness control but is less direct and effective than a procedural control like two-person control for preventing successful attacks on critical systems.

Storing chemicals behind locked doors is a physical security measure for the chemicals themselves, not a direct control for the specialized computer systems that manage them.

Maintaining calibration of the chemical sensor system ensures operational accuracy and reliability, but it is not a security control against attacks on the control system itself.