[单选题]34、 When deploying an HA or VPN load-sharing configuration using the IPsec VPN client software, which method is available?当使用IPSec VPN客户端软件配置HA或者VPN负载平衡的配置时，哪种方法可用?
A. Redundant peering 冗余对等体
B. Active/active failover active/active故障切换
C. Active/standby failover active/standby故障切换
D. VPN clustering VPN集体群