Which one of the following groups have only input devices ?

In computing, input devices are hardware components used to provide data and control signals to a computer. Output devices are hardware that translate the processed data into a human-readable form.

• Mouse: An input device used for pointing, clicking, and navigation.
• Keyboard: An input device used for entering text, numbers, and commands.
• Scanner: An input device that optically scans images or text and converts them into digital data.

On the other hand, Printers, Projectors, and Monitors are output devices because they display or produce physical copies of the information processed by the computer. Since Option D contains only a Mouse, Keyboard, and Scanner, it is the only group consisting exclusively of input devices.