This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Urachus fistula is a remanant of ? 
Select and explain. 
A. Yolk sac, B. Allantois, C. Chorion, D. Amnion
B: Allantois
Answer: B: Allantois 
Explanation: Urachus fistula is a remnant of allantoic diveiculum If patent urachus in adults, urine dribbles from umbilicus known as wheeping umbilicus Inderbir Singh's Human embryology Pg 97