Which of the following commands is the best for testing the connectivity of the crossover cable?

You are the MegaCorp Security Administrator. This company uses a firewall cluster, consisting of two cluster members. The cluster generally works well but one day you find that the cluster is behaving strangely. You assume that there is a connectivity problem with the cluster synchronization cluster link (cross-over cable). Which of the following commands is the best for testing the connectivity of the crossover cable?

A.
telnet <IP address of the synchronization interface on the other cluster member>

B.
ifconfig -a

C.
ping <IP address of the synchronization interface on the other cluster member>

D.
arping <IP address of the synchronization interface on the other cluster member>