This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
[{'content': 'K-complex is seen in which stage of sleep cycle- \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 * Full awake and alert state - Beta rhythm* Awake, eye closed and mind wandering but with less attentiveness - Alpha - rhythm* Stage 1 NREM - Theta rhythm* Stage 2 NREM - Sleep spindles, K complex* Stage 3 & 4 NREM (Deep sleep) - Delta rhythm* REM sleep - Beta rhythm and sometimes also reappearance of alpha rhythm.", 'role': 'assistant'}]