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: Medicine
[{'content': 'Stimulation of which of the following areas of brain is experimentally used to control intractable pain - \nSelect and explain. \nA. Periaqueductal grey matter, B. Mesencephalon, C. Subthalmic nucleus, D. Medical fore brain bundle', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]