This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Medicine
[{'content': 'The most common hormone other than gastrin contained in the gastric secreting islet cell tumour is: \nSelect and explain. \nA. ACTH, B. Glucagon, C. Melanocyte stimulating hormone, D. Growth hormone releasing factor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: aRef: Harrison, 14th ed, p. 1613', 'role': 'assistant'}]