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: Pathology
[{'content': 'Which of the following inhaled occupational pollutant produces extensive nodular pulmonary fibrosis ? \nSelect and explain. \nA. Silica, B. Asbestos, C. Wood dust, D. Carbon', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Silica", 'role': 'assistant'}]