Final answer:
The cochlea discerns pitch differences because different sound frequencies cause distinct areas of the basilar membrane to vibrate, in accordance with place theory.option Basilar membrane
Step-by-step explanation:
The cochlea detects differences in the pitch of sound because different frequencies vibrate different areas along the basilar membrane.
The mechanical properties of the basilar membrane change along its length, which causes it to vibrate at different places depending on the frequency of the sound wave. High-frequency sounds cause vibrations closer to the oval window, while lower frequencies lead to vibrations nearer to the apex of the cochlea. Hair cells, which are auditory receptor cells, are arranged on the basilar membrane and are most sensitive to specific frequencies of sound waves. This mechanism of pitch perception is known as the place theory.