The correct answer is C. Input-Output device.
An input-output device is a peripheral that allows a computer to communicate with the outside world. Input devices allow data to be entered into the computer, while output devices allow data to be displayed or printed. Some common input devices include keyboards, mice, and scanners. Some common output devices include monitors, printers, and speakers.
The ALU (arithmetic logic unit) is a part of the CPU that performs arithmetic and logical operations on data. The CPU (central processing unit) is the main processing unit of the computer. It is responsible for carrying out the instructions of the computer program.
The ALU and CPU are not input-output devices because they do not allow data to be entered into or output from the computer.