Which of the following is an example of vertical scaling in a cloud environment?

Vertical scaling (scaling up) involves increasing the resources of an existing instance. Adding an additional CPU to an existing Azure virtual machine directly enhances its processing power, which is a classic example of vertical scaling. The other options describe horizontal scaling (scaling out), which involves adding more instances of a resource. Adding an additional Azure virtual machine, an additional Azure Virtual Desktop session host, or an additional Azure App Service instance all involve deploying new, separate instances to distribute the workload, rather than enhancing a single existing instance.