Where must each entity have a current copy of its Operating Plan for backup functionality available?

The correct answer is that each entity must have a current copy of its Operating Plan available at the Primary Control Center. This requirement ensures that the core operational management has immediate access to critical information necessary for the monitoring and control of the power system. The Primary Control Center is typically the main hub for real-time operations, where operators manage the grid, respond to emergencies, and implement the Operating Plan. Having the Operating Plan readily available at this location is essential for effective decision-making and coordinated efforts during both normal operations and in unforeseen situations.

While backup functionality is important, it should be viewed in conjunction with immediate access to the plan at the Primary Control Center, which is the key location responsible for maintaining grid reliability and executing planned operational strategies. Other locations, like digital files or regional headquarters, do not fulfill the same immediate need for operational readiness that is provided at the Primary Control Center.