What is the default protocol preference for OSPF external routes?（）

A.It is used to determine which route should become active.
B.It is used to select which routing table to use for forwarding.
C.It is used to determine what routes to accept into the routing table.
D.It is used to select the best route between multiple equal cost paths.

A.OSPF has a single preference value for both internal and external routes.
B.RIP is preferred over OSPF external routes.
C.Direct, local, and static routes have the same preference value.
D.OSPF's preference value is lower than BGP (both IBGP and EBGP).

A.multicast and unicast IPv4 routes
B.ARP tables and MAC reachability
C.IP version 4 unicast routes
D.IP version 6 and IP version 4 routes