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
Squamaus cell Carcinoma of bladder is predisposed by-a)  Urolithiasisb)  Persistent urachusc)  Schistosomiasisd) Polype)  Smoking 
Select and explain. 
A. a, B. ac, C. ad, D. b
B: ac
Answer: B: ac 
Explanation: None