正解:B
To ensure that all traffic leaving AS 200 chooses Link 2 as the entry point, the engineer can manipulate the BGP attributes to make path via Link 2 more preferable. In this case, prepending AS numbers to the route advertisement will make the path appear longer and thus less preferable through Link 1. By applying route-map PREPEND with additional AS numbers on R3 for neighbor 10.1.1.1 (Link 1) and not doing so for neighbor 10.2.2.2 (Link 2), it will cause traffic to prefer entering through Link 2 which appears to have a shorter AS path. References: = This explanation is based on common BGP practices covered in Cisco's Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) curriculum, where manipulating BGP attributes such as AS_PATH is discussed as a method for influencing routing decisions.