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': 'Which of the following tests on maternal serum is most useful in distinguishing between open neural tube defects and ventral wall defects in a fetus? \nSelect and explain. \nA. Carcinoembryogenic antigen, B. Sphingomyelin, C. Alpha-feto protein, D. Pseudocholinesterase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: In patients with elevated amniotic fluid AFP to differentiate between NTD and abdominal wall defect, acetylcholinesterase and pseudocholinesterase are measured:', 'role': 'assistant'}]