After upgrading the vSphere infrastructure and VMware Tools to version 6.5, the "Upgrade VM Compatibility" option is grayed out in the vSphere Web Client. (See Exhibit.) What must the administrator do

The order in which VMware Tools is upgraded does not affect whether the VM compatibility upgrade option is available; the grayed-out state is determined solely by the VM's power state.

Restarting the ESXi host does not enable the upgrade option for a specific VM; the option requires the individual VM to be powered off, not the host to be rebooted.

Uninstalling VMware Tools has no bearing on enabling VM hardware compatibility upgrades, as the two features are independent, and removing Tools would be counterproductive.

VM hardware compatibility upgrades modify the virtual machine's configuration file to reference a newer virtual hardware version, which requires exclusive access only possible when the VM is powered off. Powering off the VM releases it from the running state and allows vSphere to safely apply the hardware version change.