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': 'Zollinger-Ellison syndrome is due to tumor of the - \nSelect and explain. \nA. α cells, B. β cells, C. PP cells, D. G-cells', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]