B) to control one camera remotely
A camera control unit (CCU) is a device that allows a camera operator or technician to remotely control the functions of a video camera. The CCU is usually located away from the camera, and is connected to the camera by a cable or wirelessly. The CCU allows the operator to control the camera's focus, iris, white balance, and other functions remotely, without physically touching the camera. This can be useful in situations where the operator needs to be located a distance away from the camera, or where the camera is mounted in a difficult-to-reach location. The CCU is typically used in television production and live events, where multiple cameras are used and it is important to be able to control them remotely.