The correct answer is D) 4. The mechanical advantage of a tackle, neglecting friction, is equal to the number of rope parts supporting the load. In the illustration D029DG, the tackle system has 4 rope parts supporting the load, therefore the mechanical advantage is 4. The other answer choices are incorrect because they do not accurately represent the number of rope parts supporting the load in the given tackle system. A mechanical advantage of 1 would indicate a single rope, 2 would indicate a 2-part tackle, and 3 would indicate a 3-part tackle, all of which do not match the 4-part tackle shown in the illustration.