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
Which of the following are the sites of poo-systemic anastomosis? 
Select and explain. 
A. Umbilicus, B. Lower end of oesophagus, C. Rectum and anal canal, D. All the above
D: All the above
Answer: D: All the above 
Explanation: Poosystemic anastomosis is also seen in the bare area of liver and posterior abdominal wall.