In the mode of cluster launching, when a complete session are not finished, if there is need to be added or further express,（ ）.
A.A、the session will be finished in the original channel without seeking a new channel
B.B、the caller will seek a new channel autoselectly
C.C、the system will redistributes idle channel for the caller
D.D、all of the above are possible
正确答案是C