This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
Subarachnoid space ends at 
Select and explain. 
A. D12, B. L2, C. L5, D. S2
D: S2
Answer: D: S2 
Explanation: The dura and arachnoid along with the subarachnoid space containing CSF extend up to 2nd sacral veebra. Below the lower border of L1 and S2 veebrae, the subarachnoid space contains 40 spinal nerve roots of L2-L5, S1-S5 and Co 1 which constitute the cauda equina. Ref: BD Chaurasia's HUMAN ANATOMY, Volume 3.