What is the bestpractice for repairing the hardware?

One of the hosts in a cluster of 10 hosts requires maintenance. This host is currently
running two virtual machines (VMs) for a total of 30% CPU utilization. What is the best
practice for repairing the hardware?

A.
place the VMs on the host in Maintenance mode

B.
place the host in Offline mode

C.
repair the server while running VMs

D.
place the host in Maintenance mode

Explanation:
vSphere Resource Management Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0, page 55.
You place a host in maintenance mode when you need to service it, for example, to
install more memory. A host enters or leaves maintenance mode only as the result of a
user request.
Virtual machines that are running on a host entering maintenance mode need to be
migrated to another host (either manually or automatically by DRS) or shut down. The
host is in a state of Entering Maintenance Mode until all running virtual machines are
powered down or migrated to different hosts. You cannot power on virtual machines or
migrate virtual machines to a host entering maintenance mode.
By placing the host in Maintenance mode you will ensure no Maintenance modems are
migrated to this server. [D above]