The correct answer is: A. Keyboard
A keyboard is an input device that allows a user to input text into a computer or other electronic device. It is one of the most common input devices, and is used for a variety of tasks, such as typing text, entering commands, and playing games.
A terminal is a computer that is connected to another computer, usually a mainframe or server. Terminals are used to enter data into the mainframe or server, and to display output from the mainframe or server.
A printer is an output device that prints text or images onto paper. Printers are used to produce hard copies of documents, such as letters, reports, and presentations.
A plotter is an output device that draws images onto paper. Plotters are used to produce high-quality drawings, such as blueprints and maps.
E. None of the above is not the correct answer, as a keyboard is an input/output device at which data enters or leaves a computer system.