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: Physiology
[{'content': 'Which of the following statements is true about REM sleep? \nSelect and explain. \nA. It forms 50% of total sleep duration, B. Sympathetic activity increases, C. Muscle tone is normal, D. dreams are not memorized', 'role': 'user'}, {'content': 'Answer: B \nExplanation: REM sleep :\n\nIt forms 20-25% of total sleep duration\nSympathetic activity increases\nDreams are well memorized\nGeneralised muscular atony, excpet extraocular muscle, muscles of Penis.', 'role': 'assistant'}]