<prompt> Vitamin B12 is essential for what aspect of blood cell reproduction;Formation of hemoglobinExtrusion of the nucleus from the normoblastsFormation of DNAActivation of erythropoietin  <response>: 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 . 