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: Medicine
[{'content': 'All are true in difinition 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: None', 'role': 'assistant'}]