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': 'Which is the commonest diameter of engagement- \nSelect and explain. \nA. Suboccipitofrontal, B. mentovertical, C. Occipito frontal, D. Submento vertical', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' ie. Sub occipitofrontal Commonest diameter of engagement Antero-posterior diameter - Sub occipito bregmatic* orSub occipitofrontal* Transverse diameter - Biparietal*", 'role': 'assistant'}]