Which command is used to display the EtherChannel interface information?

The command that displays the EtherChannel interface information is the one that provides a summary of all EtherChannels configured on a Cisco switch or router, showing pertinent details such as the status, protocol, and member interfaces. This command allows network administrators to quickly assess the configuration and operational state of EtherChannel links.

By using the "show etherchannel summary" command, you receive vital information about each EtherChannel, including whether the interfaces in the channel are operational and which protocols (like LACP or PAgP) are in use. The summary output is essential for diagnosing potential issues or for verifying that the EtherChannel is set up correctly.

The other options do not correspond to valid commands in the Cisco IOS context. Some may sound plausible, but they either do not exist in IOS or do not provide the specific EtherChannel summary information required to effectively manage and troubleshoot EtherChannel configurations. Thus, the chosen command stands out as the only correct one for this purpose.