The correct option is
C Organ of Corti
Cochlea is the part of inner ear that contains Organ of Corti. It is a receptor organ of hearing and considered as body's microphone. It is located in inner ear. It is present on the basilar membrane which is the floor of cochlear duct. There are many sensitive hair cells present in rows on the internal side of organ of Corti. The basal ends of hair cells are in close contact with the afferent nerve fibres which transmit impulses to brain and the sound is analysed.
So, the correct answer is 'Organ of Corti'.