The OSPF RFC 3623 Graceful Restart feature allows you to configure IETF NSF in ultivendor networks. When using OSPF Graceful Restart， which mechanism is used tocontinue forwarding packets during a switchover？（）

A.The firewall does not support Cisco Discovery Protocol. You should set the switchport trunk mode ON
B.The firewall does not support Cisco Discovery Protocol. You should set the switchport trunk mode to OFF
C.The firewall does not support Cisco Discovery Protocol. You should set the switchport trunk mode asauto.
D.The firewall does not support DTP. You should set the switchport trunk mode to ON

A.0.0.0.1
B.0.255.0.1
C.2001：DB8：：1
D.2001：DB8：ABCD：FEEF：：1