This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory, Subject name: Medicine
[{'content': 'All are true in definition of chronic bronchitis except: \nSelect and explain. \nA. Cough 3 months, B. Productive cough, C. More than 2 consecutive months, D. Haemoptysis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans: dRef: Harrison, 15thed, p. 1491, CMDT, 2004 p. 232', 'role': 'assistant'}]