This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
[{'content': 'Commonest cause of non - engagement at term, in primi is: \nSelect and explain. \nA. CPD, B. Hydramnios, C. Brow presentation, D. Breech', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Engagement is said to occur when the greatest transverse diameter of the presenting part, has passed through the pelvic inlet. In all cephalic presentations, the greatest transverse diameter is always the biparietal.\nEngagement occurs in multipara with commencement of labour\xa0in the late Ist stage after rupture of membranes and in Nullipara during the last few weeks of pregnancy, i.e. ≈ 38 weeks\nIn primi’s the most common cause of non engagement at term is deflexed head or occipitoposterior position followed by cephalopelvic disproportion (CPD).\nSince deflexed head or occipitoposterior is not given in option, we will go for CPD as the answer.', 'role': 'assistant'}]