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': 'Gallbladder contraction is stimulated by : \nSelect and explain. \nA. Gastrin, B. Secretin, C. Vagus, D. Cholvcvstokinin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. Cholecystokinin', 'role': 'assistant'}]