the machines that make our work easier are called simple machines. Some machines can be compound because they are a combination of more than two simple machines. For example, stapler.
Teeth are an example of a wedge. It is a simple machine which consists of two inclined planes. It is used to split apart objects.
The mechanical advantage of a wedge is more than 1.
The answer to this question would be A. Interference. This is because when two sounds with slightly different frequencies creates a periodic variation in volume.