which power state?

For Virtual Machine Compatibility upgrade, a VM needs to be in which power state?

A.
Maintenance mode

B.
Suspended

C.
Powered Off

D.
Powered On

Explanation:
https://pubs.vmware.com/vsphere-51/index.jsp?topic=%2Fcom.vmware.vsphere.upgrade.doc%
2FGUID-60768C2F-72E1-42E0-8A17-CA76849F2950.html