cat prints a file; less lets you inspect it as a pager. Leave less with q before running another command.
head and tail select a window from opposite ends. The default window can include more records than a handoff needs, so give a line count when precision matters.
A header isn't the most recent record. These exercises ask you to inspect the file and then leave a specific final record visible. For example, tail -n 1 selects the final line and head -n 2 selects the first two. Neither command needs you to load the whole file into an editor. An empty file produces no records. If a file contains fewer lines than the requested window, the command returns the available lines without inventing padding.