The correct option is B Endolymph
An otolith, also called statoconium or otoconium, is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. They are sensitive to gravity and linear acceleration. In mammals, otoliths are small particles, composed of a combination of a gelatinous matrix and calcium carbonate in the endolymph of the saccule and utricle. The inertia of these small particles causes them to stimulate hair cells, when the head moves.