This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Gynaecology & Obstetrics
[{'content': 'The following are related to face presentation except \nSelect and explain. \nA. The commonest position is LMA, B. Engaging diameter is submentobregmatic, C. The diameter distending the vulval outlet is mentoveical!, D. During moulding, there is elongation of occipitofrontal diameter', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The engaging diameter is submentobregmatic (9.4cm).In face presentation,the biparietal diameter is 7cm behind the face unlike in veex,where it is only 3-4cm distant.The biparietal diameter will pass through the inlet only when the face is low down in the perineum (refer pgno:372 sheila textbook of obstetrics 2 nd edition)', 'role': 'assistant'}]