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': 'Transitional cell carcinomas can be caused by ? \nSelect and explain. \nA. Napthylamine, B. Smoking, C. Bilharziasis, D. All', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'a' i.e., Napthylamine; 'b' i.e., Smoking & 'c' i.e., Bilharziasis", 'role': 'assistant'}]