Which of the following devices is not considered an input device?

The device that is not considered an input device is a CRT, which stands for Cathode Ray Tube. A CRT is a type of display technology used in older monitors and televisions. Its primary function is to output visual information to the screen, displaying graphics and text generated by the computer or device. In contrast, input devices like a mouse, light pen, and keyboard are designed to allow users to interact with and provide data to a computer system.

Input devices collect user input, which is then processed by the computer to perform various actions. The mouse allows users to click and navigate on the screen, the light pen enables drawing or selection directly on the display, and the keyboard is used for typing text and issuing commands. Since the CRT does not perform any input functions but strictly serves to convey output, it clearly falls outside the category of input devices.