[单选题]32、 Which of the following are available for use when deploying a stateful HA solution for Easy VPN? (Choose all that apply.)当为Easy VPN配置一个基于状态的HA方案时，下面的哪些可用?(选出所有满足条件的答案)
A. Active/active failover active/active故障切换
B. Redundant peering 冗余对等体
C. VPN clustering VPN 集群
D. Active/standby failover active/standby故障切换