Concept:The lever principle involves a rigid bar that turns about a fixed point called a fulcrum.Explanation:A claw hammer acts as a lever because the handle pivots about the head to pull out a nail.A wheelbarrow is a type of lever with the wheel acting as the fulcrum.Sugar tongs also form two levers joined at a common fulcrum.A single pulley, however, uses a rope looped over a grooved wheel; it does not consist of a rigid bar turning about a fulcrum.Thus, a single pulley does not apply the lever principle.Answer:C. Single pulley