Which of the following set contains only input devices?

Correct option is A

Input devices send data to the computer for processing. A keyboard captures text/commands, a mouse captures pointing/click actions, and a scanner digitizes physical documents/images into data. These peripherals do not render computer output back to the user; they primarily feed signals inward. By contrast, printers, speakers and monitors are output devices that present processed information. Therefore, only option (a) lists exclusively input devices.
Important Key Points
1. Input devices: Keyboard, mouse, scanner, microphone, webcam, barcode reader—provide data to the system.
2. Output devices: Monitor, printer, speakers, projector—display or reproduce processed results.
3. I/O combos: Some devices can be both (e.g., touchscreens are input and output), but not in the given sets.
4. Use cases: Scanners digitize paperwork for OCR; keyboards/mice control UI navigation and data entry.
5. Advantages: Dedicated input devices improve accuracy (e.g., scanner vs manual typing), speed and ergonomics.
6. Disadvantages: Each adds hardware cost and may require drivers/ports; scanners can be bulky and slower than camera capture.
Knowledge Booster
· Why (b) is wrong: Includes printer and speaker, both output devices.
· Why (c) is wrong: Printer, speaker and monitor are all output devices.
· Why (d) is wrong: Includes printer (output), so the set isn’t input-only.
· For exams, remember “KMS” (Keyboard–Mouse–Scanner) as a quick mnemonic for an all-input trio.