The correct answer is B) for that sailor to feed the hauling part through a bosun's chair hitch. This is the safest and most controlled way for a sailor to be lowered in a bosun's chair when descending vertically. The bosun's chair hitch allows the sailor to feed the hauling part through the chair, providing them with direct control over their descent rate and the ability to stop or slow their descent as needed. This method is preferred over options that rely on rails, cleats, or winches, which introduce more risk and reduce the sailor's control over the lowering process. The other answer choices, while potentially functional, do not provide the same level of safety and control for the sailor being lowered. Option A involves leading the bight to a rail, which reduces the sailor's control, and Option C and D use mechanical means that are less responsive to the sailor's needs during the descent.