Which Cisco CRS 4.0 server configuration task enables the Cisco CRS server to fail over to a secondary Cisco Unified CallManager when the primary Cisco Unified CallManager fails?（）

A.The LDAP directory must have a secondary profile configured.  
B.No special configuration is required. Cisco Unified CallManager maintains the failover.  
C.The JTAPI provider on the Cisco CRS server must be configured with the secondary Cisco Unified CallManager IP address following the primary Cisco Unified CallManager IP address.  
D.There must be a second JTAPI user configured with an alternate range of CTI ports.