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
[{'content': 'Posterior superior iliac spine is at the level of? \nSelect and explain. \nA. L5, B. S1, C. S2, D. S3', 'role': 'user'}, {'content': 'Answer: C \nExplanation: PSIS is at level of S2BD CHOURASYA&;S HUMAN ANATOMY 6TH EDITION VOLUME 2 PAGE NO:430', 'role': 'assistant'}]