Neutropenia develops in a patients undergoing cancer chemotherapy. Administration of which one of the following agents would accelerate recovery of neutrophil counts.

B. i.e. (Filgrastim) (484 - Lippincott's 3rd)FILGRASTIM - is a human granulocyte- colony- stimulating factor that can act on hematopoietic cells to stimulate proliferation. If regulates production of neutrophils in the bone marrow and thus, is effective in reversing neutropenia in patients undergoing cancer chemotherapy* Leucovorin, the N5 N10 derivative of tetra hydrofolic acid and vitamin B!2 although they would be effective in the treatment of anemias, do not increase neutrophil counts* The gluco corticoid, prednisone is also ineffective