This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous System, Subject name: Pediatrics
[{'content': 'Which is the best marker for NTD? \nSelect and explain. \nA. aFP, B. hCG, C. Pseudocholinesterase, D. Inhibin-A', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. aFP(Ref: Nelson's 20/e p 2802)Prenatal screening of maternal serum for AFP in the 16th-18th wk of gestation is an effective method for identifying pregnancies at risk for fetuses with neural tube defects in utero.", 'role': 'assistant'}]