With GETVPN, if a key server is configured to use multicast as the rekey transport mechanism, then under which of these conditions will the key server retransmit the rekey messages?

With GETVPN, if a key server is configured to use multicast as the rekey transport mechanism, then under which of these conditions will the key server retransmit the rekey messages?
A . It never retransmit the rekey messages.
B . It only retransmit the rekey message when it does not receive the rekey acknowledgment from at least one group member.
C . It only retransmit the rekey message when it does not receive the rekey acknowledgment from all group member.
D . It only retransmit the rekey message when DPD to the group members fails.
E . It always retransmit the rekey message.

Answer: E