After upgrading an ESX host to vSphere 4, which of the following three actions should
be taken (Choose Three)

A.
restore files to the service console

B.
connect the host to vCenter if managed

C.
boot into Troubleshooting Mode for proper operation

D.
configure licensing

E.
verify virtual machine operation

Explanation:
vSphere Upgrade Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0 vSphere Client 4.0, page
79.
After you upgrade an ESX/ESXi host, consider the following:
right-clicking the host in the vCenter Server inventory and selecting Connect.
for 60 days. You must assign an upgraded license to your product within 60 days after
the upgrade. Use the License Portal and the vSphere Client to configure licensing.
There is no requirement to restore files to the service console after an upgrade
Troubleshooting mode is not a valid mode for a vSphere host
It makes sense to verify virtual machine operation after an upgrade has taken pace.