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: Surgery
Kasai's procedure is performed in 
Select and explain. 
A. Type 4B choledochal cyst, B. Type 3B choledochal cyst, C. Type 5 choledochal cyst, D. Type 2 choledochal cyst
A: Type 4B choledochal cyst
Answer: A: Type 4B choledochal cyst 
Explanation: It is performed in in type 4b witches only extrahepatic biliary tree dilation.