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': 'Open Neural tube defect is best diagnosed by: \nSelect and explain. \nA. USG, B. Maternal serum alpha fetoprotein, C. X-ray, D. Amniotic fluid acetycholinesterase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Amniotic fluid acetycholinesterase', 'role': 'assistant'}]