This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Pathology
A 52-year-old recent immigrant from Vietnam complains of abdominal swelling, weight loss, and upper abdominal pain of 3 weeks in duration. His past medical history includes malaria and infection with the liver fluke Clonorchis sinensis. The liver is hard on palpation. An abdominal CT scan shows a hypo-attenuated mass with lobulated margins in the liver. A biopsy discloses well-differentiated neoplastic glands embedded in a dense fibrous stroma. Which of the following is the most likely diagnosis? 
Select and explain. 
A. Carcinoma of the gallbladder, B. Cholangiocarcinoma, C. Hemangiosarcoma, D. Hepatocellular carcinoma
B: Cholangiocarcinoma
Answer: B: Cholangiocarcinoma 
Explanation: Carcinoma originates anywhere in the biliary tree. Cholangiocarcinoma:- Arising within the liver Associated with substantial fibrosis Confused with metastatic carcinoma and reactive fibrosis. These tumors occur at an increased frequency in persons infected with the liver fluke C. sinensis The other choices are not associated with a history of C. sinensis infestation.