This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special Senses: Hearing and Equilibrium, Subject name: Physiology
[{'content': 'The Extracellular fluid that has high potassium and low sodium is? \nSelect and explain. \nA. Synovial fluid, B. Endolymph, C. Ectolymph, D. CSF', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (B) Endolymph > The inner ear (labyrinth) is made up of two parts, one within the other. The bony labyrinth is a series of channels in the petrous portion of the temporal bone. Inside these channels, surrounded by a fluid called perilymph, is the membranous labyrinth.> This membranous structure more or less duplicates the shape of the bony channels. It is filled with a K+-rich fluid called endolymph, and there is no communication between the spaces filled with endolymph and those filled with perilymph.', 'role': 'assistant'}]