Which of the following commands is most useful for viewing large files?

The less command is most useful for viewing large files. The less command displays the output of a file one page at a time. Viewing large files through cat may take more time to scroll pages, so it is better to use the less command to see the content of large files.

Answer option B is incorrect. The cat command is also used to view the content of a file, but it is most useful for viewing short files.

Answer option A is incorrect. The cp command is used to copy files and directories from one location to another.

Answer option D is incorrect. The touch command is not used to view the content of a file. It is used to create empty files or to update file timestamps.