An administrator is configuring a stretched HA cluster. The administrator wishes to restrict the
failover of VMs to certain hosts within a given site.
Which additional vSphere feature satisfies this requirement?

A.
vSphere Distributed Switch

B.
Distributed Resource Scheduler

C.
Datastore Clusters

D.
Host Folders

Explanation:
http://pubs.vmware.com/vsphere-4-esxvcenter/index.jsp?topic=/com.vmware.vsphere.availability.doc_41/c_useha_works.html(see using
VMware HA and DRS Together)