This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pathology
Klatskin tumor is- 
Select and explain. 
A. Nodular type of cholangiocarcinoma, B. Fibrolarnellar hepatocellular carcinoma, C. Gall bladder carcinoma, D. Hepatocellular carcinoma
A: Nodular type of cholangiocarcinoma
Answer: A: Nodular type of cholangiocarcinoma 
Explanation: Cholangiocarcinoma is classified into two: 1.Intrahepatic 2.Extrahepatuc: which is divided into- Perihilar tumors: these are known as Klatskin tumors and are located at the junction of the right and left hepatic ducts forming the common hepatic duct. Distal bile duct tumors: they arise near the ampulla of Vater REF: GENERAL AND SYSTEMIC PATHOLOGY RAMDAS NAYAK FIRST EDITION PAGE 468 IMAGE REF: