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
Umbilical vesicle attains full development in - 
Select and explain. 
A. 2 week, B. 4 week, C. 6 week, D. 7 week
B: 4 week
Answer: B: 4 week 
Explanation: None