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': 'Which is the least common site for the occurance of berry aneurysm? \nSelect and explain. \nA. Anterior communicating aery, B. Middle cerebral aery, C. Veebral aery, D. Basilar aery', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 85% of berry aneurysms occur in the anterior circulation, mostly on the Circle of Willis. 3 most common anterior locations are over : anterior communicating aery, posterior communicating aery and middle cerebral aery. 10% of it occur over basilar aery and only 5% occur on veebral aery. Reference: Handbook of Neurosurgery By Mark Greenbergpage 1055.', 'role': 'assistant'}]