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': "The following is true of Robe's pelvis : \nSelect and explain. \nA. Triradiate pelvis, B. Single ala absent, C. Both alae absent, D. Wide pelvic brim", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Both alae absent', 'role': 'assistant'}]