What is the procedure to upgrade all Cisco SD-WAN devices to a recent version?

What is the procedure to upgrade all Cisco SD-WAN devices to a recent version?
A . The upgrade is performed for a group of WAN Edge devices first to ensure data-plabe availability when other controllers are updated.
B . The upgrade is performed first on vManage, then on WAN Edge devices, then on vBond and finally on vSmart The reboot must start from WAN Edge devices.
C . Upgrade and reboot are performed first on vManage then on vBond then on vSmart. and finally on the Cisco WAN Edge devices.
D . Upgrade and reboot are performed first on vBond. then on vSmart. and finally on the Cisco WAN Edge devices.

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Answer: C