N the auditory system, sound vibrations are transduced into electrical energy by hair cells in the inner ear. Sound vibrations from an object cause vibrations in air molecules, which in turn, vibrate the ear drum. These vibrations then pass into the cochlea, the organ of hearing.
a, because exercise doesn't just aid the prevention of certain diseases, it helps prevent many diseases. i would've chosen d if it wasn't so specific but a is the correct answer.
