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': 'Shoest diameter of the pelvic outlet is : \nSelect and explain. \nA. Interspinous diameter, B. Antero posterior diameter, C. Posterior sagittal diameter, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Posterior sagittal diameter', 'role': 'assistant'}]