The correct option is A organ of corti
Cochlea is the part of internal ear responsible for hearing. It is a spirally coiled structure that resembles a snail shell in appearance. Cochlea has organ of corti, which contains hair cells that act as auditory receptors.
Semicircular canals are membranous canals suspended in the perilymph of the bony canals and help in providing equilibrium (balancing).
Pinna is part of outer ear and it helps to collect sound waves.
Ear ossicles are found in the middle ear and they increase the efficiency of transmission of sound waves to the inner ear.