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 is not a boundary of calot triangle 
Select and explain. 
A. Common hepatic duct, B. Cystic duct, C. Right lobe of liver, D. Gall bladder
D: Gall bladder
Answer: D: Gall bladder 
Explanation: Gall bladder