When viewing the show etherchannel summary command output, what does the 'S' signify in the output of 'Po1 (SD)'?

A) Layer 3 EtherChannel
B) Layer 2 EtherChannel
C) Standby state
D) Suspended state

B
Explanation: B) The output ('Po1 (SD)') shown from the show etherchannel summary command signifies that the EtherChannel uses the PortChannel 1 interface, it is layer 2 (the 'S'), and it is down (the 'D').