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': "Pneumothorax is not a usual occurance with which of the following conditions? \nSelect and explain. \nA. Asthma, B. Marfan's syndrome, C. Bronchopulmonary aspergillosis, D. Positive pressure ventilation", 'role': 'user'}, {'content': "Answer: C \nExplanation: The most common of secondary spontaneous pneumothorax is chronic obstructive pulmonary disease, which accounts for approximately 70% of cases. Other causes include diseases of the airways (chronic obstructive pulmonary disease, acute severe asthma, cystic fibrosis), infections of the lung (Pneumocystis pneumonia (PCP), tuberculosis, necrotizing pneumonia), interstitial lung disease (Sarcoidosis, idiopathic pulmonary fibrosis, histiocytosis X), connective tissue diseases (Rheumatoid ahritis, ankylosing spondylitis, polymyositis and dermatomyositis, systemic sclerosis, Marfan's syndrome and Ehlers-Danlos syndrome) and Ca bronchus.", 'role': 'assistant'}]