<prompt> Periodic acid schiff stain shows block positiveity in -MyeloblastsLymphoblastsMonoblastsMegakaryoblasts  <response>: Ans. is b i.e., LymphoblastImpoant characteristics of Leukemic cellso Myeloblast -o Myeloperoxidase positive, Auer rod positive, Sudan Black B o Monoblast -- Nonspecific exterase positiveo Lymphoblast -- Periodic acid schiff PAS positive 