单项选择题

A. CGMP version 2 is being used.
B. The switch will use sparse mode first, dense mode second.
C. A rendezvous point must be configured in order for the interface to operate in sparse mode.
D. IGMP version 2 is being used.
E. The rendezvous point is IP address 172.16.4.16.
F. If a rendezvous point is configured, the interface cannot operate in dense mode.