Here's a problem to solve: Many common hand tools create a mechanical advantage by using the basic principles found in simple machines. For example, a screwdriver uses the principles of the wheel and axle. In order to increase gripping force, pliers use the principle demonstrated in the

Among the 4 following options, which is the correct answer?

- A: pulley.
 
- B: lever.
 
- C: wedge.
 
- D: screw.
 