This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuroanatomy, Subject name: Anatomy
[{'content': 'Sub-arachnoid space ends at \nSelect and explain. \nA. S2 level, B. L5 level, C. S1 level, D. L3 level', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) S2 level> Subarachnoid space surrounds the brain & spinal cord, and ends below at the lower border of the second sacral vertebra.', 'role': 'assistant'}]