In Cisco Unified Communications Manager presence with SIP, if the presence entity resides within the Cisco Unified Communications Manager cluster, how does Cisco Unified Communications Manager respond to a SIP line-side presence request?
A. by sending a SIP NOTIFY message to the presence watcher to indicate the current status of the presence entity
B. by sending a SIP SUBSCRIBE message to the presence watcher to request the presence status of the indicated presence entity
C. by sending SCCP messages to the presence watcher to indicate the current status of the presence entity
D. by using the Cisco Unified Presence PUBLISH Trunk service parameter on Cisco Unified Communications Manager to associate the user with a line appearance
