This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'Sleep spindles and K complexes occur in which phase of the sleep cycle? \nSelect and explain. \nA. REM, B. Stage I, C. Stage II, D. Stage III', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Stage II- Low voltage, mixed frequency background with sleep spindles (12-14 cps bursts) and K complexes (negative sharp wave followed by positive slow wave)', 'role': 'assistant'}]