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': 'Endoscopy is useful in diagnosis of peptic ulcer in following sutuations except - \nSelect and explain. \nA. Post bulbar ulcer, B. Stomal ulcers, C. Giant duodenal ulcer, D. Duodenal erosion', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]