正解:A
HSRPv1 (Hot Standby Router Protocol version 1) is designed to allow for transparent failover of the first-hop IP router. HSRP provides high network availability by providing redundancy for IP traffic from hosts on networks. In a group of router interfaces, the active router is the router of choice for routing packets; the standby router is the router that takes over the routing duties when an active router fails or when preset conditions are met. This ensures that traffic continues to flow even if one router fails, making it a suitable choice for the scenario described in the question.
References:
* Configuring HSRP, VRRP, and GLBP - Cisco
* Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) - Cisco