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: Surgery
Sq. cell tumor of urinary bladder is due to -a) Stoneb) Schistosomiasisc) Chr. cystitisd) Diabetes mellitus 
Select and explain. 
A. ab, B. bc, C. abc, D. bcd
C: abc
Answer: C: abc 
Explanation: Risk factors for squamous cell ca of bladder

Schistosoma haematobium
it's a risk factor for both TCC & sq. cell ca, but more for sq. cell ca.
Chronic irritation from urinary calculi, long term indwelling catheters, chronic urinary infections
Bladder diverticula