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': 'EEG shows "Sleep Spindles" in this stage of NREM sleep \nSelect and explain. \nA. I, B. II, C. III, D. IV', 'role': 'user'}, {'content': 'Answer: B \nExplanation: (B) II > Stage II of NREM sleep is characterized by sleep spindles on EEC. Sleep spindles are bursts of alpha-like, 10-14Hz., 50 mV waves.> When a person falling asleep enters stage I of "NREM, the EEG shows low-amplitude, high frequency waves. As the progression from Stage I to Stage IV of NREM occurs, the frequency of waves decreases while the amplitude increases progressively.', 'role': 'assistant'}]