Which of the following is a valid object to add an extent to?

A.
an existing VMFS or NFS datastore

B.
an existing NFS datastore

C.
an existing VMFS datastore

D.
an available unused storage volume

Explanation:
What’s New in VMware vSphere 4.0 .
vStorage VMFS Volume Grow – vCenter Server 4.0 allows dynamic expansion of a
VMFS volume extent to add capacity to an existing datastore. VMFS Volume Grow is a
new method for expanding a datastore without disrupting running virtual machines. After
a LUN that backs that datastore is expanded through an array management utility, the
administrator can use VMFS Volume Grow to expand the VMFS extent on the expanded
LUN.