The correct answer is A. Light pen.
A light pen is a hand-held input device that allows a user to interact with a computer by pointing to displayed objects. It works by detecting light from a cathode ray tube (CRT) screen. When the light pen is pointed at a particular spot on the screen, the computer can determine the x- and y-coordinates of that spot. This information can then be used to select an object on the screen, enter text, or control the cursor.
Optical-wands are similar to light pens, but they use a laser beam instead of light from a CRT screen. This makes them more accurate than light pens, but they are also more expensive.
Plotter is a computer output device that produces hard copy drawings. It is used to create high-quality drawings, such as blueprints and maps. Plotters are typically used in engineering, architecture, and other fields where accurate drawings are required.
The answer is A. Light pen.