What does "line protocol is up" specifically indicate about the interface?

An administrator issues the show ip interface s0/0 command and the output displays that interface Serial0/0 is up, line protocol is up.

What does "line protocol is up" specifically indicate about the interface?
A . The cable is attached properly.
B . CDP has discovered the connected device.
C . Keepalives are being received on the interface.
D . A carrier detect signal has been received from the connected device.
E . IP is correctly configured on the interface.

View Answer

Answer: C