Which of the following is both an input and output device?

 A touch-screen monitor is a device that can function as both an input and output device. An input device is a device that allows users to enter data or commands into a computer or system. An output device is a device that displays or produces data or information from a computer or system. A touch-screen monitor can function as an input device by detecting the touch or gesture of the user on the screen and sending the corresponding signal to the computer or system. A touch-screen monitor can also function as an output device by showing visual information on the screen. A microphone, a speaker, and a keyboard are not devices that can function as both an input and output device. A microphone is an input device that allows users to record sound or voice into a computer or system. A speaker is an output device that plays sound or voice from a computer or system. A keyboard is an input device that allows users to type text or characters into a computer or system. References: CompTIA IT Fundamentals+ Study Guide: Exam FC0-U61, Second Edition, Chapter 3: Computing Components, page 106.