Which of the following devices is not purely an output device because, in modern systems, it can also be used to accept input from the user?

Introduction / Context:
Traditionally, computer hardware was clearly divided into input and output devices, but many modern devices perform both roles. For example, some screens now allow users to interact directly by touching them. This question asks you to identify which device is not purely an output device because, in practice, it can also serve as an input device. Understanding this helps you handle questions about hybrid devices in basic computer knowledge exams.

Given Data / Assumptions:

• The options list several common output devices: printer, speaker, plotter, screen and projector.
• The phrase not purely output suggests a device that can also accept input in some common configuration.
• We interpret screen as including modern touch screen monitors.
• The context is everyday computing with contemporary hardware.

Concept / Approach:
Printers, speakers, plotters and projectors are classic output devices: they take data from the computer and present it as printed pages, sound, plotted drawings or projected images. Users do not normally send information back into the computer through these devices. A screen or monitor, however, can be purely output in its traditional form, but many modern screens incorporate touch functionality. A touch screen monitor both displays output and detects touch input, acting as a combined input-output device. Therefore, among the listed options, the screen (touch screen monitor) is the one that is not purely an output device.

Step-by-Step Solution:

Verification / Alternative check:
Device classification tables in modern computer fundamentals often mention touch screen as an example of a device that is both an input and an output device. It outputs visual content like any monitor but also inputs touch coordinates, allowing gestures and taps to control the system. Printers, speakers, plotters and projectors are consistently categorised as output only. Manufacturers market touch screen laptops, tablets and kiosks as having direct touch input, confirming the dual role of the screen in these systems. This real world usage supports the conclusion that a screen can be both input and output, and therefore is not purely an output device.

Why Other Options Are Wrong:

• Printer: Designed solely to output text and graphics onto paper; it does not accept user input for processing.
• Speaker: Outputs sound from the computer; it does not capture or send input data to the system.
• Plotter: Used to create high precision drawings on paper; it is a specialised output device.
• Projector: Projects visual output onto a large screen; users cannot input information through the projector itself.

Common Pitfalls:
Some students might remember older definitions where monitor or screen is listed strictly as an output device and not consider modern touch technology. Exam setters increasingly acknowledge that touch screens exist and may phrase questions as not purely output to highlight these hybrid devices. To avoid confusion, think about the actual data flow: if a device can send information back into the computer based on user actions, then it has an input role. Touch screens clearly meet this condition, unlike the other devices listed.

Final Answer:
The device that is not purely an output device, because it can also accept user input, is the Screen (touch screen monitor).