Peak bandwidth usage is the most helpful in defining an early-warning threshold associated with insufficient network bandwidth. Peak bandwidth usage is the maximum amount of data that istransferred over a network connection at a given time. It indicates the highest demand and stress on the network resources and capacity. By monitoring the peak bandwidth usage, the organization can identify the potential bottlenecks, slowdowns, and disruptions that may occur due to insufficient network bandwidth. The organization can also plan and allocate the network bandwidth accordingly to meet the peak demand and avoid service degradation. The other options are not as helpful as peak bandwidth usage, as they do not reflect the actual or potential network performance issues that may arise due to insufficient network bandwidth. References = Risk and Information Systems Control Study Manual, Chapter 4: Risk and Control Monitoring and Reporting, Section 4.3: Key Risk Indicators, page 197.