This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Cancer, Subject name: Pharmacology
Neutropenia develops in a patients undergoing cancer chemotherapy. Administration of which one of the following agents would accelerate recovery of neutrophil counts. 
Select and explain. 
A. Leucovorin, B. Filgrastim, C. Prednisone, D. Vitamin B12
B: Filgrastim
Answer: B: Filgrastim 
Explanation: 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