This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'Vaginal delivery is allowed in all except: \nSelect and explain. \nA. monochorionic monoamniotic twins, B. First twin cephalic and second breech, C. Extended breech, D. Mento anterior', 'role': 'user'}, {'content': 'Answer: A \nExplanation: <p> Monochorionic monoamniotic twins are one of the main indication for elective Caesarean section. Reference:Textbook of obstetrics,Sheila Balakrishnan,2nd edition,page no:188. <\\p>', 'role': 'assistant'}]