The EIGRP stub connected option is appropriate when the new circuit is intended to protect reachability to a connected subnet without turning the router into a broad transit point. EIGRP stub routing is used to limit the routes a router advertises to its neighbors and to constrain EIGRP query scope. A stub router can advertise connected routes, summary routes, redistributed routes, or combinations depending on the configured stub option. In this scenario, the new C-to-D circuit protects connectivity to 10.0.4.0/24 during a failure between B and D. Advertising the connected network through the stub behavior gives upstream routers a valid alternate route while still preventing unnecessary transit advertisements. Stub redistributed would be used for routes learned from another routing process, not for directly connected networks. Stub receive-only would prevent the router from advertising any routes, which would not protect reachability. Stub leak-map is used for controlled exceptions and is unnecessary if the required route is a connected subnet. Reference topics: EIGRP stub routing, connected route advertisement, query boundary design, DUAL stability.