This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gallbladder and Extrahepatic Biliary Tract, Subject name: Pathology
Which of the following is premalignant to cholangiocarcinoma - 
Select and explain. 
A. Biliary' intraepithelial neoplasia, B. Mucinous cystic neoplasms, C. Intraductal pappilary biliary' neoplasia, D. All the above
D: All the above
Answer: D: All the above 
Explanation: Ans. is 'd' i.e., All the above o Premalignant lesions for cholangiocarcinoma are also known, the most important of which are bibary intraepithelial neoplasias (low to high grade, BilIN-1, -2, or -3).o BilIN-3, the highest grade lesion, incurs the highest risk of malignant transformation.o More rare are mucinous cystic neoplasms and intraductal papillary biliary> neoplasia