正解:B
To force traffic through a specific path, one can manipulate routing policies and attributes. In the context of BGP (Border Gateway Protocol), the local preference attribute is used to prefer an outbound path from a local AS (Autonomous System). The higher the local preference value, the more preferred the route is. In this scenario, setting a higher local preference on R1 for routes received from R3 will make R1 prefer R3 as the next hop over R2 for reaching network 172.16.10.0/24.
References := Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) v1.1