This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Surgery
[{'content': 'Smoking is a risk factor for all cancer except: \nSelect and explain. \nA. Esophagus, B. Urinary bladder, C. Pancreas, D. Gallbladder', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Smoking is not the risk factor for carcinoma gallbladder. Smoking is the risk factor for all gastrointestinal tract malignancies and hepatobiliary pancreatic tract malignancies except carcinoma gallbladder.', 'role': 'assistant'}]