This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fetal Skull and Maternal Pelvis, Subject name: Gynaecology & Obstetrics
[{'content': 'Longest diameter of fetal skull is: \nSelect and explain. \nA. Biparietal, B. Bitemporal, C. Occipito temporal, D. Submentovertical', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. is d, i.e. SubmentoverticalRef. Dutta Obs 9/e p 77-78Remember:Smallest diameterLongest diameterIst = Bimastoid diameterIInd = Bitemporal diameterIst = Mento verticalIInd = Submento vertical/occipitofrontal', 'role': 'assistant'}]