<prompt> Longest fetal diameter:BiparietalSuboccip tobregmaticOccipitofrontalMentovertical  <response>: Ans is d, i.e. MentoverticalFetal diameters-AP diameters are always longer than Transverse diameter of fetal head.Longest diameter is-Mentovertical diameter 14 cms followed by submentovertical diameter. 