Which ability does the Survivable Remote Site Telephony feature provide?

A.	a means to allow the local site to continue to send and receive calls in the event of a WAN failure
B.	a means to route calls on-net through other sites during high utilization periods
C.	a method that allows for backup calls in the event that your gateway fails
D.	the ability to force a call out of a certain trunk when the Cisco Unified Communications Manager is being upgraded