The correct answer is C) being raised too high. The boom stops on a pedestal crane are designed to prevent the boom from being raised beyond a certain height. This is a safety feature to prevent the boom from exceeding its maximum allowable angle or height, which could lead to instability, structural failure, or dangerous situations. The boom stops limit the upward travel of the boom, ensuring it does not go beyond its safe operating range. The other answer choices are incorrect because they do not accurately describe the primary function of the boom stops. The boom stops do not prevent the boom from swinging at sea (A), being lowered too low (B), or overloading when not in use (D). These are other safety features or operational considerations, but they are not the main purpose of the boom stops.