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: Physiology
[{'content': 'Guanylin is secreted by : \nSelect and explain. \nA. C-cells., B. Paneth cells., C. Neurohypophysis., D. All of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Paneth cells are endocrine cells located in crypts of lieberkuhn.', 'role': 'assistant'}]