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: Medicine
[{'content': 'Marker for biliary tract obstruction - \nSelect and explain. \nA. Alkaline phosphatase, B. Aspaate transaminase, C. Alanine transaminase, D. Creatinine kinase', 'role': 'user'}, {'content': "Answer: A \nExplanation: Answer-A. Alkaline phosphataseEnzymes that reflect cholestasisAlkaline phosphatase5'- nucleotidaseGamma-glutamyl transpeptidase (GGT)Lipoprotein-X is an abnormal lipoprotein that appears in the sera of patients with obstructive jaundice and thus is a sensitive indicator of cholestasis.", 'role': 'assistant'}]