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
Which of the following inhaled occupational pollutant produces extensive nodular pulmonary fibrosis? 
Select and explain. 
A. Silica, B. Asbestos, C. Wood dust, D. Carbon
A: Silica
Answer: A: Silica 
Explanation: None