How is sound transmitted from the outer ear to the brain?

Sound is transmitted from the outer ear to the brain through a complex process primarily involving vibrations that are converted into electrical signals. When sound waves enter the outer ear, they hit the eardrum, causing it to vibrate. These vibrations are transferred through three tiny bones in the middle ear, known as the ossicles, which amplify the sound.

Once the vibrations reach the inner ear, specifically the cochlea, they cause fluid within the cochlea to move. This movement stimulates hair cells, which convert the mechanical vibrations into electrical signals. These signals travel along the auditory nerve to the brain, where they are interpreted as sound.

This process highlights the importance of vibration and conversion to electrical signals in the transmission of sound, which is why this option is the correct answer. The other options do not accurately reflect the biological mechanisms involved in sound transmission, such as chemical messages or direct contact with sound waves.