This error is generated when a vSphere administrator takes a VM snapshot:

An error occurred while taking a snapshot: Failed to quiesce the virtual machine

What should the administrator investigate to determine the cause of the failure?

A. Check if the virtual machine is already running on snapshots.

B. Check if the virtual machine is in suspended state.

C. Check if VMware Tools is installed on virtual machine.

D. Check if the virtual machine has an ISO mounted.