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
MC site of gastrinoma:- 
Select and explain. 
A. Duodenum, B. Pancreas, C. Stomach, D. Colon
A: Duodenum
Answer: A: Duodenum 
Explanation: Agastrinomais a gastrin-producing tumor usually located in the pancreas or the duodenal wall. Gastric acid hypersecretion and aggressive, refractory peptic ulceration result (Zollinger-Ellison syndrome).Diagnosisis by measuring serum gastrin levels. Treatment is proton pump inhibitors and surgical removal.