An OSPF transit network is a network that has at least two routers that are connected by a multi-access link and can forward traffic for other networks1.A transit network is different from a stub network, which has only one router connected to it and does not forward traffic for other networks2.A transit network is also different from a virtual link, which is a logical connection between two areas that are not physically adjacent2.A transit network is not necessarily connected to a different routing protocol, althoughit can be if the router performs redistribution2. Therefore, the correct answer is C. A network on which a router discovers at least one neighbor.