The correct answer is C) gravity davit. A limit switch is a safety device that is typically found on gravity davits, which are used to launch and retrieve lifeboats and other survival craft. The limit switch is designed to automatically stop the movement of the davit when the craft has reached the desired position, preventing it from going too far and potentially causing damage or injury. The other answer choices, such as radial davits, sheath-screw davits, and liferaft cradles, do not typically require the use of a limit switch for their operation, as they utilize different mechanisms for launching and retrieving survival craft.