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
[{'content': 'A 70 year old patient with history of smoking presents with gross painless\nhematuria. Likely diagnosis is \nSelect and explain. \nA. Uerter stone, B. Ca. bladder, C. Ca. prostate, D. Bladder stone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: History of smoking, old age and gross hematuria it is likely to be bladder Ca.', 'role': 'assistant'}]