Essential files of MS DOS are A. Command.com B. Io.sys C. Msdos.sys D. All of above

The correct answer is D. All of above.

Command.com is the command-line

interpreter that allows users to interact with the operating system. Io.sys is the input/output system driver that manages the hardware devices on the computer. Msdos.sys is the main file of MS-DOS that contains the operating system’s core code.

Without these three files, MS-DOS would not be able to function.