While configuring Call Survivability in Cisco Unified Communications Manager, what step is mandatory to reach remote sites while in SRST mode?
A. Enable Cisco Remote Site Reachability.
B. Configure CFUR.
C. Enable the SRST checkbox in the MGCP gateway.
D. Configure the H.323 gateway for SRST in Cisco Unified Communications Manager.
E. Enable the Failover Service parameter.