How many times will the right end of a lever move up and down if the cam makes four rotations?

To determine how many times the right end of a lever moves up and down when the cam makes four rotations, it's essential to understand the relationship between the rotations of the cam and the movements of the lever.

Typically, in mechanisms where a cam is involved, each complete rotation of the cam can result in a corresponding movement of the lever. If the cam is designed to lift the lever once during each complete rotation, then for four total rotations of the cam, the lever will move in response to each of those rotations. Hence, the lever will complete four full up-and-down movements, aligning with the four rotations of the cam.

This understanding of mechanical coupling between the cam and the lever is crucial for solving similar problems involving gears or levers connected to rotary elements. Therefore, the correct answer reflects that the right end of the lever will move up and down four times alongside the four rotations of the cam.