This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Female Sterilization, Subject name: Gynaecology & Obstetrics
[{'content': 'The most common site of ligation in female sterilisation is: \nSelect and explain. \nA. Isthmus, B. Ampullary, C. Cornual, D. Fimbrial', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e. Isthmus Ligation and Tubectomy in the process of tubal sterilization is most commonly preferred in the proximal isthumic portion of the fallopian tube.", 'role': 'assistant'}]