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
Longest diameter of fetal skull is: 
Select and explain. 
A. Biparietal, B. Bitemporal, C. Occipito temporal, D. Submentovertical
D: Submentovertical
Answer: D: Submentovertical 
Explanation: 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