Which three IP multicast group concepts are true?（）

• A、If a packet is sent to a multicast group address, the multicast frame contains the source multicast address.
• B、A router does not have to be a member of a multicast group to recei ve multicast data.
• C、A router must be a member of a multicast group to send to the group.
• D、A router does not have to be a member of a multicast group to send to the group.
• E、If a packet is sent to a multicast group address, all members of the multic ast group will receive it.
• F、A router must be a member of a multicast group to receive multicast data.