Inclined plane Pulley Wedge Lever
I gave my students this multiple choice question: When you bend your arm at the elbow, the bones and muscles in your arm are acting as a system. What simple machine does this system represent?

Only one answer is correct among these 4 choices:
- Inclined plane
- Pulley
- Wedge
- Lever

Could you tell me which one is correct?

Lever