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: Anatomy
[{'content': 'Circle of willis is formed by \nSelect and explain. \nA. Anterior cerebral artery, posterior communicating artery, middle cerebral artery, posterior cerebral artery, internal carotid artery, B. Anterior cerebral artery, posterior communicating artery, internal carotid artery, anterior communicating artery, middle cerebral artery., C. Anterior communicating artery, posterior communicating artery, internal carotid artery, anterior inferior cerebellar artery, anterior cerebral artery., D. Anterior communicating artery, posterior communicating artery, internal carotid  artery, posterior cerebral artery, anterior cerebral artery.', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Middle cerebral artery doesn’t form circle of willis.', 'role': 'assistant'}]