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': 'Persistent occipitoposterior is common in the following type of pelvis: \nSelect and explain. \nA. Android pelvis, B. Anthropoid pelvis, C. Gynaecoid pelvis, D. Platypelloid pelvis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In more than 50% of cases, the occipito-posterior position is associated with either an anthropoid or android pelvis. Persistent occipitoposterior is an abnormal mechanism of the occipito-posterior position where there is malrotation of the occiput posteriorly towards the sacral hollow (occipito-sacral position). Delivery may occur spontaneously as face-to-pubis but arrest may occur in this position and is called occipito-sacral arrest. Ref: Textbook of Obstetrics by D C Dutta, 6th edition, Page 365, 369.', 'role': 'assistant'}]