This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Physiology
[{'content': 'Beta cells of pancreas produce: \nSelect and explain. \nA. Glucagon, B. Gastrin, C. Insulin, D. Pancreatin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C', 'role': 'assistant'}]