What is the purpose of IGMP in a multicast implementation?（）
- A it is not used in multicast
- B it determines the virtual address group for a multicast destination
- C it dynamically registers individual hosts in a multicast group on a specific LAN
- D it is used on WAN connections to determine the maximum bandwidth of a connection
- E it determines whether Bidirectional PIM or PIM sparse mode will be used for a multicast flow