This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sleep Physiology, Subject name: Physiology
[{'content': 'Sleep spindle is seen in- \nSelect and explain. \nA. REM, B. Stage 1 NREM, C. Stage 2 NREM, D. Stage 3 NREM', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans is 'c' i.e., Stage 2 NREM o Full awake and alert state - Beta rhythmo Awake, eye closed and mind wandering but with less attentiveness - Alpha - rhythmo Stage 1 NREM - Theta rhythmo Stage 2 NREM - Sleep spindles, K complexo Stage 3 & 4 NREM (Deep sleep) - Delta rhythmo REM sleep - Beta rhythm and sometimes also reappearance of alpha rhythm.", 'role': 'assistant'}]