This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Posterior superior iliac spine is at the level of 
Select and explain. 
A. L5, B. S1, C. S2, D. S3
C: S2
Answer: C: S2 
Explanation: PSIS line identifies the S2 spinous process most frequently