A、Before sending traffic, it must first join  multicast group 239.1.1.1 by sending an IGMPv2 membership report to the default router on the local subnet.

B、It must send an IGMPv2 Request to Send  packet and then wait for an IGMPv2 Clear to Send packet from the IGMPv2 querier router on the local subnet

C、It may begin transmitting multicast traffic to the group only when there is no other host transmitting to the group on the local subnet.

D、It may transmit multicast traffic to the group at any time.