Which three IP multicast group concepts are true？ （Choose three.） （）

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