Concept:A pointing device is an input hardware that enables the user to control and move the cursor on the computer screen.
Explanation:A trackball is a pointing device that consists of a ball housed in a fixed socket.
The user rotates the ball with their fingers or palm, and the cursor moves in the corresponding direction on the screen.
The device itself stays stationary, so only the ball needs to move.
This makes a trackball ideal for laptops, portable devices, and users who find a conventional mouse difficult to use.
Let us compare it with the other listed options.
A plotter is an output device used to print large graphics and drawings.
A keyboard is an input device used to type characters and enter data.
A monitor is an output device used for displaying visual information.
None of these devices is primarily built to control cursor movement.
Therefore, the trackball is the only option that acts as a cursor-control pointing device.
Answer:A. Trackball