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: Unknown
[{'content': 'Vitamin B12 is essential for what aspect of blood cell reproduction; \nSelect and explain. \nA. Formation of hemoglobin, B. Extrusion of the nucleus from the normoblasts, C. Formation of DNA, D. Activation of erythropoietin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Within 6-9 hours of treatment with vitamin B12 formation of nuclear DNA component promotes normoblastic reaction of the bone marrow, Folic acid also promotes the formation of nucleic acids .', 'role': 'assistant'}]