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: Anatomy
[{'content': 'Caudal end of neuropore closes by \nSelect and explain. \nA. 24th day, B. 27th day, C. 32nd day, D. 40th day', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]