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
Urachus fistula is - 
Select and explain. 
A. Patent allantois, B. Ectopic hernia, C. Patent vitello-intestinal tract, D. Meckel's diverticulum
A: Patent allantois
Answer: A: Patent allantois 
Explanation: None