Which of the following is an example of an output device?

An output device is a piece of hardware that takes processed data from a computer and converts it into a format that can be understood by the user. In this context, a speaker serves as an output device because it converts digital audio signals from the computer into sound that can be heard. This function is crucial in various applications, such as playing music, sound alerts, or any audio output that requires user perception.

The other devices mentioned have different roles: a mouse is an input device, allowing the user to interact with the computer; a keyboard is also an input device used for typing and entering commands; and a scanner functions as an input device that converts physical documents into digital format. These distinctions clarify the role each device plays in a computer system, solidifying the understanding of how input and output devices operate together within technology.