Why are sound waves classified as mechanical waves?A They can travel through a vacuum.B They require a medium.C They are able to do work.D They transfer energy.

Sound waves are classified as mechanical waves because they require a medium to travel through. Unlike electromagnetic waves such as light or radio waves, which can travel through a vacuum, sound waves are disturbances that move through a medium such as air, water, or a solid object. This is because sound waves are created by the vibration of an object, which creates a disturbance in the surrounding medium. This disturbance then travels through the medium as a wave of pressure changes, which we perceive as sound. Therefore, the correct answer is B: They require a medium.