This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
[{'content': 'The most commonest cause for chronic cor pulmonale is \nSelect and explain. \nA. Recurrent pulmonary embolization, B. COPD, C. cystic fibrosis, D. Bronchial asthma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref Harrison 19 th ed pg 1505 Once patients with chronic pulmonary or pulmonary vascular disease develop cor pulmonale, the prognosis worsens. Although chronic obstructive pulmonary disease (COPD) and chronic bronchitis are responsible for approximately 50% of the cases of cor pulmonale .', 'role': 'assistant'}]