To filter the output of the ‘show logging’ command to include entries related to a specific access control list, Peter should use the ‘include’ keyword followed by the access list number. The correct command would be ‘show logging | include 210’. This command will display all log entries that contain the string ‘210’, which is the number of the access control list he wants to monitor.

References: The use of the ‘include’ keyword in Cisco router commands is a standard method for filtering show command outputs to display only lines that contain a specified string or pattern. This is covered in Cisco’s documentation and training materials related to router commands and access control list management12.