The correct answer is D) main switchboard. The main switchboard is the central part of the shipboard electrical system that is used to control the distribution of power to the various branch circuits throughout the vessel. It contains the circuit breakers, fuses, and other control devices that regulate and distribute the electrical power from the generators to the different systems and equipment on the ship. The other answer choices are incorrect because: A) disconnect links are not used to control power distribution, B) the bridge control panel is for controlling the ship's navigation and steering systems, not the electrical distribution, and C) the governor relay box is part of the engine control system, not the electrical system.