When a router running BGP receives a route with an unreachable next hop, what should I do?

When a router running BGP receives a route with an unreachable next hop, what should I do?
A . Send an error message to the router that issued the Update.
B . Refused to join the BGP routing table and silently discarded.
C . Receive the route and add it to the BGP routing table. But this route will not be preferred by BGP and will not join the IP routing table.
D . Receive the route, join the BGP routing table, and participate in the BGP routing rules. It may be optimized as the best route and join the IP routing table.

Answer: C