This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Obstetrics, Subject name: Gynaecology & Obstetrics
[{'content': 'The shoest diameter in fetal head is: \nSelect and explain. \nA. Biparietal diameter, B. Bimastoid diameter, C. Occipito frontal diameter, D. Bitemporal Diameter', 'role': 'user'}, {'content': 'Answer: B \nExplanation: IMPOANT FETAL SKULL PARAMETERS Sub occpito brematic 9.5 cms : Sub mento bregmatic 9.5 cms Biparietal diameter 9.5 cms Mento veical 14 cms Submento veical 10cms Bi temporal diameter 8 cms Bimastoid: 7.5 cms', 'role': 'assistant'}]