Which item is an input device?

A scanner is a peripheral device that captures images from physical objects, such as documents or photographs, and converts them into digital data that a computer can process. Its fundamental function is to send information to the computer system, which is the definition of an input device. Unlike storage devices that handle both input and output, a scanner's primary role is unidirectional data input.

A. Printer: A printer is an output device; it receives data from a computer to create a physical copy.

B. Flash Drive: A flash drive is a storage device, not purely an input device, as it performs both read (input) and write (output) functions.

C. CD: A Compact Disc is a storage medium; the associated drive is an I/O (input/output) device that can read from and write to the disc.

1. Patterson, D. A., & Hennessy, J. L. (2017). Computer Organization and Design: The Hardware/Software Interface (5th ed.). Morgan Kaufmann. In Chapter 1, Section 1.4, "Under the Covers," the authors classify devices like scanners as input devices and printers as output devices, distinguishing them from storage.

2. Null, L., & Lobur, J. (2021). The Essentials of Computer Organization and Architecture (6th ed.). Jones & Bartlett Learning. Chapter 1, Section 1.3.2, "I/O and Storage," categorizes input devices as those that "allow the user to communicate with the computer," providing scanners as a key example.

3. MIT OpenCourseWare. (2016). 6.0001 Introduction to Computer Science and Programming in Python, Fall 2016. Lecture 1: What is Computation? The lecture materials describe the basic components of a machine, defining input devices as the mechanism for getting data into the machine.