<prompt> Vaginal delivery is allowed in all except:monochorionic monoamniotic twinsFirst twin cephalic and second breechExtended breechMento anterior  <response>: 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 