Which of the following is not the input unit of the computer?

Correct option is C

Input devices are those that allow users to enter data into the computer. Devices like a mouse, keyboard, and scanner serve this purpose. The screen (monitor), however, is an output device, as it displays information from the computer rather than feeding data into it. Modern touchscreens can function as both input and output devices, but traditionally, the screen is classified as output-only.