Answer:
4. wedge and lever
Explanation:
Simple machines are mechanical devices which make our work easier. Examples are : lever, wedge, wheel and axel, pulley, screw and an incline plane.
A stapler is a made up of a level which is the handle part and a wedge which are the staples.
A pulley is a simple machine that has one or more wheels connected with a rope in a loop to make lifting of loads easier because it changes the direction of force applied/pull thus multiplying the force applied. <em>A stapler does not have the wheel and the rope thus answer choice 1 and 2 are incorrect.</em>
A screw is a simple machine that applies torque on a shaft to produce a large axial force on the load. It utilizes the conversion of rotational motion to a linear motion and a torque to a linear force. <em>A stapler mechanism does not involve rotational motion or rotational force, hence answer option 3 is incorrect.</em>
