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
Transitional cell carcinomas can be caused by ? 
Select and explain. 
A. Napthylamine, B. Smoking, C. Bilharziasis, D. All
D: All
Answer: D: All 
Explanation: Ans. is 'a' i.e., Napthylamine; 'b' i.e., Smoking & 'c' i.e., Bilharziasis