正解:B
The customer's requirements include FHRP redundancy, a multivendor router environment, and support for IPv4 and IPv6 hosts. VRRP (Virtual Router Redundancy Protocol) version 2 is the appropriate protocol to meet these requirements. It provides FHRP redundancy to increase the availability of routing paths via automatic default gateway selections on an IP subnetwork. VRRP version 2 supports both IPv4 and IPv6, making it suitable for environments that utilize both IP versions. Additionally, being a standard protocol, it supports a multivendor router environment. References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide