In a data center environment, a network engineer is tasked with analyzing the performance metrics of a newly deployed application. The application is expected to handle a peak load of 10,000 transactions per minute (TPM). During the initial testing phase, the engineer observes that the application is processing 8,000 TPM with an average response time of 200 milliseconds. To ensure optimal performance, the engineer decides to implement a monitoring solution that provides real-time analytics and assurance metrics. Which of the following metrics would be most critical for the engineer to monitor in order to assess the application\'s performance and identify potential bottlenecks?