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: ENT
[{'content': 'The sleep apnea syndrome is defined as - \nSelect and explain. \nA. 30 or more episodes of apnea during 12 hours sleep, B. 28 or more episodes of apnea during 7 hours sleep, C. 30 or more episodes of apnea during 7 hours sleep, D. 30 or more episodes of apnea during 10 hours sleep', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]