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: Gynaecology & Obstetrics
[{'content': 'For operative vaginal delivery, what is the level of sensory block needed to cover pain? \nSelect and explain. \nA. T10-L1, B. T10-S1, C. L1-S1, D. S2-S4', 'role': 'user'}, {'content': "Answer: D \nExplanation: Vaginal delivery :The first stage of labor requires a sensory block to the level of the umbilicus . During the second stage of labor and for operative vaginal delivery, a sensory block of S2 through S4 is usually adequate to cover pain from perineal stretching and/or instrumentation. (Ref: William's Obstetrics; 25th edition)", 'role': 'assistant'}]