This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Stomach & Duodenum, Subject name: Surgery
[{'content': 'A 45-year-old man presents with an upper gastrointestinal bleed. An upper endoscopy reveals multiple duodenal ulcers and an enlarged stomach. \nSelect and explain. \nA. Glucagonoma, B. Insulinoma, C. Zollinger-Ellison syndrome (ZES), D. Watery diarrhea, hypokalemia, and achlorhydria (WDHA) syndrome', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Gastrinoma, or ZES, should be suspected in patients with peptic ulcer disease refractory to medical treatment, or in patients with multiple ulcers or ulcers in uncommon locations. Gastrin secretion by the tumor, most commonly found in the pancreas, results in hypersecretion of gastric acid. Common patient complaints are epigastric pain, melena, hematemesis, diarrhea, and weight loss. ZES may occur as part of the MEN-1 syndrome; this patient presents with only atypical peptic ulcer disease. Omeprazole is the treatment of choice for control of peptic ulcers in ZES.', 'role': 'assistant'}]