The show ip ospf database external command displays information about which OSPF LSA type？（）

A.Packet mode
B.Frame mode
C.Transparent mode
D.Channel mode
E.Tunnel mode

A.It removes the top label in the MPLS label stack.
B.It adds a top label in MPLS label stack.
C.It replaces the top label in the MPLS label stack with another value.
D.It replaces the top label in the MPLS label stack with a set of labels.
E.None of above.