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': 'Ventouse application, the prerequisite is : \nSelect and explain. \nA. Full dilatation of cervix, B. Station +2, C. Premature, D. Head engaged', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Head engaged', 'role': 'assistant'}]