This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerves of Lower Extremity, Subject name: Anatomy
[{'content': 'Nerve root of pudendal nerve is- \nSelect and explain. \nA. S1 S2 S3, B. S2 S3 S4, C. S3-S4, D. S2-S3', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., S2 S3 S4 o Has been explained in previous session", 'role': 'assistant'}]