What is one requirement when adding an extent to a VMFS datastore?

A.
A new unused NFS mount

B.
An RDM with sufficient space available

C.
An unused iSCSI or FCP LUN

D.
Free space on the LUN holding the VMFS datastore

Explanation:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=display
KC&externalId=1017662