This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anaesthesia
[{'content': 'Pudendal nerve block \nSelect and explain. \nA. S1-3, B. S2-4, C. S3-5, D. S4,5', 'role': 'user'}, {'content': "Answer: B \nExplanation: Pudendal Nerve BlockIt is a peripheral nerve block that provides local anesthesia over S2-4 dermatomes (majority of perineum and inferior quaer of vagina)It does not block the superior bih canal so the mother is able to feel the uterine contractions(Refer: Morgan and Mikhail's Clinical Anaesthesiology, 5th edition, pg no.847)", 'role': 'assistant'}]