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 sleepa) Alphab) Betac) Deltad) Theta \nSelect and explain. \nA. ab, B. a, C. ad, D. bc', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Stages of sleep and rhythm\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Beta rhythm- Alert, awake, maximum concentration.\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Alpha rhythm- Eyes closed, mind wandering, less attentiveness\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Theta rhythm- Stage 1 NREM\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Sleep spindles, K complex- Stage 2 NREM\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Delta rhythm- Deep sleep (Stage 3 & 4 NREM)\n\xa0\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Beta Rhythm and occasional reappearance of alpha rhythm- REM', 'role': 'assistant'}]