a thinner nut is tightened down over a thicker or main nut and the main nut is tightened against the thinner nut by loosening
a slot is cut in line with the centre of each face and a split pin passes through two slots in the nut and a hole in the bolt, so that a positive lock is obtained unless the pin shears
a slot is cut about half way through the nut and a small screw is tightened between the nut and the bolt in order to produce more friction
the bottom cylindrical
✅ The correct answer is option B.