The correct option is D Both (a) and (b)
The inner ear consists of a labyrinth of channels within a skull bone (the temporal bone). The part of the inner ear involved in hearing is cochlea. The cochlea has two large chambers, an upper vestibular canal and a lower tympanic canal, separated by a smaller cochlear duct.The vestibular and tympanic canals filled with perilymph, while cochlear duct is filled with endolymph.