The answer is C - Organ of Corti.
Organ of Corti is considered as body's microphone. It is present on basilar membrane which is floor of cochlear duct. Mechanoreceptors of ear are present in organ of Corti. On the internal side of organ of Corti, many hair cells are present. These hair cells are the sensory receptors for sound. When there is fluid motion in the ear due to sound waves, these hair cells generate electric signals which are then sent to brain and sound is perceived.
