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
Smoking is a risk factor for all cancer except: 
Select and explain. 
A. Esophagus, B. Urinary bladder, C. Pancreas, D. Gallbladder
D: Gallbladder
Answer: D: Gallbladder 
Explanation: 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.