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': 'EEG rhythm recorded from the surface of the scalp during REM sleep - \nSelect and explain. \nA. Alpha, B. Beta, C. Delta, D. Theta', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Beta', 'role': 'assistant'}]