DEL command is used to

Answer: Option A

In Disk Operating System (DOS), the DEL command is used to delete files. When you enter "del filename" at the command prompt in DOS, it deletes the specified file from the current directory.

Option B, "Delete directory," is not done with the DEL command in DOS. To delete a directory, the command is typically "rmdir" or "rd" in DOS.
Option C, "Delete labels," is not a function of the DEL command in DOS.
Option D, "Delete contents of file," is not the primary purpose of the DEL command, which deletes entire files rather than just their contents.

Therefore, the correct answer is Option A: Delete files.