The correct option is C Perilymph
The bony labyrinth is the cavity of the inner ear. It consists of the central vestibule, the semicircular canals, and the cochlea. Inside the bony labyrinth lies a complicated membranous sac called the membranous labyrinth. The small space between the wall of the bony labyrinth and the wall of the membranous labyrinth is filled with a fluid called perilymph. The space within the membranous labyrinth is filled with endolymph.