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': 'Biggest fetal skull diameter is \nSelect and explain. \nA. Biparietal, B. Bitemporal, C. Mento vertical, D. Submentobregmatic', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Mento vertical', 'role': 'assistant'}]