Which of the following is an example of an input device in a computer?

Correct option is B

A touchscreen is an example of an input device because it allows users to interact with the computer by touching the screen, effectively sending input commands to the computer.
(a) Monitor: This is incorrect because a monitor is an output device, not an input device. It displays visual information from the computer to the user.
(c) Printer: This is incorrect because a printer is also an output device, used to produce physical copies of documents from the computer.
(d) Speaker: This is incorrect because speakers are output devices that emit sound produced by the computer.