This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Inner ear contain endolymph and perilymph. Which of the following structure of the inner ear produces endolymph? \nSelect and explain. \nA. Is a filtrate of blood serum, B. Is secreted by Stria vascularis, C. Is secreted by Basilar membrane, D. Is secreted by Hair cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Endolymph fills the entire membranous labyrinth and resembles intracellular fluid, being rich in K ions. It is secreted by the secretory cells of the stria vascularis of the cochlea and by the dark cells (present in the utricle and near the ampullated ends of semicircular ducts).', 'role': 'assistant'}]