Which command is used to copy a directory and its contents?

The command that is used to copy a directory and its contents is the one that includes the option "-r." This option stands for "recursive" and is essential when dealing with directories in Unix-like operating systems such as Linux. By using the "-r" option with the cp command, you instruct the system to not only copy the directory itself but also all of its files and subdirectories. Thus, it ensures that the entire directory tree is duplicated at the destination.

For instance, if you have a directory named "dir1" containing several files and subdirectories, executing "cp -r dir1 dir2" will create a copy of "dir1" inside "dir2," preserving the entire structure and contents of "dir1."

The standard cp command without the -r option would only be able to copy individual files, and attempting to use it on a directory would result in an error. Additionally, the mv command is used for moving files and directories, not for making copies, while "copy" is not a valid command in Linux; it is more commonly associated with DOS or Windows environments. Thus, the command that successfully accomplishes the task of copying a directory and its contents is indeed the cp command with the recursive option.