Which of the following is an input device?

An input device is a hardware component that allows users to enter data or commands into a computer system. A scanner fulfills this definition because it captures images from physical documents and converts them into a digital format that the computer can process. This enables the transfer of visual information into the computer for further use, such as editing, storage, or sharing.

In contrast, a monitor is an output device that displays visual information processed by the computer. A printer serves a similar purpose, as it takes digital information and outputs it onto physical media, like paper. Similarly, a speaker converts digital audio signals into sound, making it an output device as well. Understanding the distinct roles of input and output devices is essential for grasping how computers interact with users and other systems.