What system can ensure at least two people are aware of changes in water distribution protocols?

A secondary password system is designed primarily to enhance security by requiring an additional layer of authentication for access to sensitive information or systems. While it can involve multiple individuals being aware of login protocols, it does not inherently ensure that two people are aware of changes in water distribution protocols.

In contrast, an automated alert system is a proactive approach where notifications regarding changes in water distribution protocols can be sent automatically to designated personnel. This ensures that multiple staff members receive real-time updates, allowing for timely awareness and response to any modifications.

A chain of command defines the hierarchy and responsibility within an organization, which is essential for operational effectiveness. While it facilitates communication regarding changes, it does not guarantee that two individuals are informed simultaneously about protocol changes.

A redundancy system involves maintaining backup systems or processes to ensure reliability and continuity, but it does not directly pertain to communication and awareness of protocol changes.

Therefore, while the other options do provide some level of security or communication, they do not effectively ensure that at least two people are continuously updated on changes in water distribution protocols like an automated alert system would.