A 39 year old coal miner who smokes, drinks and has a family history of bladder cancer is suffering from BPH. The most important risk factor for his bladder carcinoma is?

The key is B. Smoking. [Risk factors of bladder cancer: i) Smoking ii) Exposure to chemicals used in dye industry iii) Whites are more likely to develop bladder cancer iv) Risk increases with age v) More common in men vi) Chronic bladder irritation and infections (urinary infections, kidney and bladder stones, bladder catheter left in place a long time.) vii) Personal history of bladder or other urothelial cancer viii) Family history ix) Chemotherapy or radiotherapy x) Pioglitazone for more than one year and certain herb xi) Arsenic in drinking water xii) Low fluid consumption].