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 most impoant point of reference in the use of forceps is : \nSelect and explain. \nA. The Plane of greatest dimension, B. Posterior sagittal diameter, C. Pelvic axis, D. Station of biparietal diameter', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Station of biparietal diameter', 'role': 'assistant'}]