[单选题]55、 When deploying an HA solution for VPN, which method can provide you with stateful failover?当为VPN配置一个HA方案时，哪种方法可以提供基于状态的故障切换?
A. Active/active failover active/active故障切换
B. Active/standby failover active/standby故障切换
C. Redundant peering 冗余对等体
D. Redundancy with routing 带有路由的冗余