How Does a BGP Router Process a Received Route Whose

How does a BGP router process a received route whose next hop is unreachable?

A) The BGP router sends an error message to the router that has sent the update message.
B) The BGP router accepts the route and adds it to the BGP routing table. This route, however, is neither preferred nor added to the IP routing table for packet forwarding.
C) The BGP router refuses the route.
D) The BGP router accepts the route and adds it to the BGP routing table. This route participates in route selection and may be selected as the optimal route to be added to the IP routing table for packet forwarding.