Which is a valid requirement for deploying the vCenter Server Appliance 6.x to a DRS cluster? 

Answer options:

A. At least one host in the cluster must be in maintenance mode or lockdown mode.
B. One ESXi host in the cluster must not be in maintenance mode or lockdown mode.
C. All ESXi hosts in the cluster must not be in maintenance mode.
D. One ESXi host in the cluster must not be in lockdown mode.

D