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
Vaginal delivery is allowed in all except: 
Select and explain. 
A. monochorionic monoamniotic twins, B. First twin cephalic and second breech, C. Extended breech, D. Mento anterior
A: monochorionic monoamniotic twins
Answer: A: monochorionic monoamniotic twins 
Explanation: <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>