This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: COPD and Asthma, Subject name: Medicine
[{'content': 'The complication least likely to occur in a case of chronic bronchitis is: \nSelect and explain. \nA. Pulmonary hypeension, B. Spontaneous pneumothorax, C. Respiratory acidosis, D. Polycythemia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Spontaneous pneumothorax is a complication of rupture of a bulla in an emphysematous patient. Chronic hypoxia in chronic bronchitis leads to pulmonary aery hypeension and cor pulmonale. CO2 retention leads to respiratory acidosis. Long term hypoxia leads to increased hemoglobin production leading to polycythemia.', 'role': 'assistant'}]