Which is a valid requirement for deploying the vCenter Server Appliance 6.x to a DRS cluster?
A. One ESXi host in the cluster must not be in maintenance mode or lockdown mode.
B. At least one host in the cluster must not be in maintenance mode or lockdown mode.
C. One ESXi host in the cluster must not be in lockdown mode.
D. All ESXi hosts in the cluster must not be in maintenance mode.
D！
If you want to deploy the appliance on a DRS cluster of the inventory of a vCenter Server instance, verify that the cluster contains at least one ESXi host that is not in lockdown or maintenance mode.
Reference:
https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.install.doc/GUID-8F62E118-4805-4B0A-904C-C561C1A692E7.html
Argue A and not B if B says “must be in maintenance mode”