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
Caudal end of neuropore closes by 
Select and explain. 
A. 24th day, B. 27th day, C. 32nd day, D. 40th day
B: 27th day
Answer: B: 27th day 
Explanation: None