Refer to the exhibit. A network engineer is designing a network for AS100. The design should ensure that all traffic enters AS100 via link 1 unless there is a network failure. In the event of a…

Modifying the next-hop attribute on R3 primarily affects how next-hop reachability is communicated to BGP peers but does not directly influence external path preference for incoming traffic in the same way AS-Path prepending does.

Using AS-Path prepending on R3 would make Link 1 less preferred for incoming traffic, which contradicts the requirement for Link 1 to be the primary path.

Modifying the next-hop attribute on R4 has a similar effect to option A; it does not directly influence external path preference for incoming traffic to establish Link 2 as a backup path.

Using AS-Path prepending on R4 when advertising routes out via Link 2 will artificially lengthen the AS-Path for those routes. External BGP peers prioritize paths with shorter AS-Paths, thus they will prefer Link 1, making Link 2 the designated backup.