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: Pathology
Which of the following is called as Klatskin's tumor 
Select and explain. 
A. Fibrolamellar hepatocelluar carcinoma, B. Hilar cholangiocarcinoma, C. Gall bladder adenocarcinoma, D. Intrahepatic cholangiocarcinoma
B: Hilar cholangiocarcinoma
Answer: B: Hilar cholangiocarcinoma 
Explanation: Perihilar cholangiocarcinoma is also called Klatskin tumors. They occur at the bifurcation of right and left hepatic ducts.