A 42 -year old man was referred with a 2 week history of fever weakness and bleeding gum. Peripherial smear showed pancytopenia. The bone marrow examinationrevelaed 26% blasts frequently exhibiting Auer rods andmature myeloid cells. An occasional neutrophil withpseudo Pelger-Huet anomaly was also noted : Which ofthe following cytocheimcal stains is most likely to bepositive ?