This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chronic Myelogenous Leukemia, Subject name: Pathology
In chronic myeloid leukemia CML, serum vitamin B12 level is: 
Select and explain. 
A. Slightly decreased, B. Normal, C. Markedly decreased, D. Increased
D: Increased
Answer: D: Increased 
Explanation: Biochemical abnormalities in CML include a low leukocyte alkaline phosphatase score and high levels of vitamin B12, uric acid, lactic dehydrogenase, and lysozyme.