The answer is B. External commands.
External commands are commands that are not built into the operating system. They are stored in files on the disk and must be loaded into memory before they can be executed. This means that they require additional files to perform specific operations.
Internal commands, on the other hand, are built into the operating system. They are stored in memory and do not require additional files to be loaded.
Valuable commands are commands that are considered to be important or essential. They are often used by system administrators and other power users.
Primary commands are commands that are used to perform basic operations, such as copying files or creating directories.
Here are some examples of external commands:
ls: List the contents of a directory.cp: Copy a file.mv: Move a file.rm: Delete a file.
Here are some examples of internal commands:
cd: Change directory.pwd: Print the current working directory.echo: Display a message.exit: Exit the shell.