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': "Caplan's syndrome is pneumoconiosis with \nSelect and explain. \nA. Lymphadenopathy, B. Congestive cardiac failure, C. Rheumatoid ahritis, D. HIV", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pulmonary manifestations of RA include pleurisy with or without effusion, ILD in up to 20% of cases, necrobiotic nodules (nonpneumoconiotic intrapulmonary rheumatoid nodules) with or without cavities, Caplan syndrome (rheumatoid pneumoconiosis), pulmonary hypeension secondary to rheumatoid pulmonary vasculitis, organized pneumonia, and upper airway obstruction due to cricoarytenoid ahritis. Ref Harrison 19th edition pg 1713', 'role': 'assistant'}]