Percentage CPU is the correct metric to most directly indicate the VM's CPU usage.

That metric reports the percentage of CPU capacity used by the virtual machine across its cores and it is the standard Azure Monitor metric for CPU utilization so it directly reflects how busy the VM's processors are.

Processor Queue Length measures the number of threads waiting for processor time and it can indicate contention but it does not directly show the proportion of CPU in use so it is not the best choice for reporting CPU usage.

Network In Total measures incoming network traffic in bytes and it has no direct relation to processor utilization so it will not tell you about CPU usage.

Processor Time is a Windows performance counter term that is similar in concept to CPU percentage but it is not the standard Azure Monitor metric name used for VM CPU usage and on Linux the platform metric provided for CPU utilization is Percentage CPU so Processor Time is not the right answer for this question.

Full AWS Practitioner Certification Question