What describes the storage categories represented by OpenStack Swift and EMC XtremIO requirements?

What describes the storage categories represented by OpenStack Swift and EMC XtremIO requirements?
A . Swift = Distributed Object Storage
XtremIO = Central Storage
B . Swift = Central Storage
XtremIO = Distributed File Storage
C . Swift = Distributed Block Storage
XtremIO = Distributed Object Storage
D . Swift = Distributed File Storage
XtremIO = Distributed Block Storage

Answer: A