which interface is used for communication between the Cisco Unified Presence server and the Microsoft Exchange server?

When integrating Cisco Unified Presence with Microsoft Exchange, which interface is used for
communication between the Cisco Unified Presence server and the Microsoft Exchange server?

A.
OWAWebDAV

B.
XMPP

C.
XML over HTTP

D.
XCPOWA

E.
XCPWebDAV