Which of the following is a common application of simple machines?

Simple machines are fundamental mechanical devices that help us perform work more easily by amplifying force or changing the direction of effort. Common examples of simple machines include levers, ramps, pulleys, wheels, axles, inclined planes, and wedges.

When looking at the choices presented, selecting levers and ramps as a common application of simple machines makes sense because they are two of the primary types of simple machines that either increase mechanical advantage or reduce the effort needed to perform a task. For instance, ramps allow for the transportation of heavy objects to a height with less effort than lifting directly, while levers enable the manipulation of heavy items with greater ease through the application of force at a distance from a fulcrum.

Other options like computers, automobiles, and hydraulic systems incorporate complex engineering and multiple mechanisms but do not solely represent simple machines. Instead, these choices blend simpler and more complex systems. Simple machines underpin many of the functions of these more complicated devices, but they do not exemplify simple machines in the same direct manner as levers and ramps. Thus, levers and ramps effectively illustrate the principles and applications of simple machines more clearly.