Which of the following is an example of a digital input device?

A digital input device is a piece of hardware that allows users to input data into a computer system in a digital format. The keyboard is categorized as a digital input device because it translates the physical pressing of keys into digital signals that the computer can understand and process. Each key on the keyboard corresponds to a specific digital signal, enabling users to input text, commands, and data into the computer.

In contrast, devices like the monitor and printer primarily function as output devices. The monitor displays visual information processed by the computer, while the printer generates a physical copy of digital documents. A mouse, although it is indeed an input device, often functions in an analog way by detecting movement and translating it into digital signals for cursor control, which may lead to some confusion about the nature of its input. Nonetheless, among the given choices, it is the keyboard that best exemplifies a digital input mechanism.