Refer to the exhibit.

 In the given scenario, to ensure that area 15 traffic from R5 to R1 prefers the route through R4, a multiarea adjacency should be implemented on the link between R2 and R4. The cost can be manipulated to make this path preferred. Multiarea adjacency allows OSPF routers to form adjacencies with routers in other areas, enabling more direct routing of traffic. By adjusting the cost of this adjacency, traffic can be directed preferentially through specific paths.

References: Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) study guide or course materials available on Cisco’s official website or learning network store.