This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CLL & CML, Subject name: Medicine
[{'content': 'Vitamin B12 level in chronic myeloid leukemia is: \nSelect and explain. \nA. Elevated, B. Decreased (slightly), C. Normal, D. Markedly decreased', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Chronic Myelogenous leukaemia Increased levels of Vitamin B12 levels Uric acid levels Serum LDH levels Lysozyme Decreased levels of LAP( Leukocyte Alkaline Phosphatase )', 'role': 'assistant'}]