The correct answer is B) Gun tackle. Gun tackle is a type of tackle configuration that consists of a single fixed block and a single movable block, with a rope threaded between them. This configuration provides a mechanical advantage, allowing a smaller force to be applied to lift a larger load. The other answer choices are not correct in this context. Single purchase and single luff tackle refer to different tackle configurations, while a parbuckle is a method of moving a cylindrical object, not a type of tackle.