VM1 runs a single-instance financial app App1 and experiences CPU spikes at month end. You will create a scheduled runbook to increase VM1's processor performance at month end. What action should the runbook perform?

To increase VM1's processor performance, the runbook should modify the VM size property of VM1. Changing the VM size allows you to select a larger VM SKU with more vCPUs and memory, directly addressing the CPU spikes. This is a standard method for scaling up a single VM's resources. Adding the Azure Performance Diagnostics agent would help diagnose performance issues but not resolve them. Adding VM1 to a scale set is for horizontal scaling (multiple instances) and is not applicable for a single-instance application experiencing CPU spikes. Increasing the vCPU quota for the subscription only raises the limit on how many vCPUs can be provisioned, it doesn't change the size of an existing VM. Adding a Desired State Configuration (DSC) extension is for managing VM configuration, not for dynamically resizing the VM itself.