In which type of machine does the use of levers apply?

The use of levers applies to both simple and compound machines. Simple machines include levers, which are devices that help lift or move loads with less effort by using the principle of mechanical advantage. A lever consists of a rigid beam and a fulcrum, allowing force applied at one end to lift a weight at the other end.

In compound machines, which are combinations of two or more simple machines, levers can work in conjunction with other elements like pulleys, gears, or inclined planes. This compound action enhances the overall function and efficiency of the machine.

Other options focus on specific machine types. While levers are integral to pulleys, inclined planes, as well as complex machinery, they do not exclusively represent those systems. Thus, the most comprehensive choice here recognizes that levers can be found in both simple and compound machines, reflecting their fundamental role in a broad category of mechanical systems.