What are two most likely reasons that VMs cannot power up on this host?

An administrtor has just completed an upgrade of an ESXi 5.x host. Prior to the upgrade, a backup of the host configuration was performed. After the upgrade the backup was restored to the upgraded host. Shortly the administrator receives complaints that users are unable to power on virtual machines.

What are two most likely reasons that VMs cannot power up on this host? (Choose two)

A.
The ESXi host had a corrupt installation that was never properly repaired before the backup was taken.

B.
The backup applied to the host after the upgrade was taken before the host was licenced.

C.
The backup applied to the host after the upgrade corrupted the image.

D.
The host was not licenced after the upgrade.