A 42 year old man was referred with a 2 week history of fever, weakness, and bleeding gums. Peripheral smear showed pancytopenia. The bone marrow examination revealed 26% blasts, frequently exhibiting Auer rods, and mature myeloid cells. An occasional neutrophil with the Pelger-Huet anomaly was also noted. Which of the following cytochemical stains is most likely to be positive?