正解:C
For point-to-point telepresence, asymmetric routing can create delay variation, packet reordering, and troubleshooting complexity. The design requirement is to make egress and ingress flows follow the same path. In the topology, the best way to steer traffic away from the less desirable return path is to configure a higher metric on the router in area 4 so OSPF path selection favors the symmetric path. OSPF chooses paths based on cumulative cost, and increasing the cost on the unwanted path makes the preferred path more attractive without removing redundancy. Route leaking on the routers in area 1 or area 2 would introduce additional interarea route visibility but would not necessarily solve the asymmetric flow problem. A route filter in area 4 could remove reachability or create suboptimal failure behavior rather than simply preferring the right path. Raising the metric is a cleaner design technique because it preserves backup reachability while influencing normal forwarding. Reference topics: OSPF cost design, symmetric routing, telepresence traffic, interarea path optimization, metric engineering.