**Core Concept**
Myeloblasts are immature cells in the granulocytic series, and specific stains are used to identify them in bone marrow and blood smears. Myeloperoxidase (MPO) is an enzyme present in the granules of myeloblasts, and staining for MPO helps in the diagnosis of acute myeloid leukemia (AML).

**Why the Correct Answer is Right**
The correct answer is based on the principle that MPO is a specific enzyme found in the granules of myeloblasts. MPO is involved in the production of reactive oxygen species, which is essential for the killing of ingested microorganisms by neutrophils. In the context of AML, MPO staining helps in identifying myeloblasts and distinguishing them from other types of blasts. The MPO stain is a crucial diagnostic tool in the workup of AML.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option may refer to Periodic Acid-Schiff (PAS) stain, which is used to identify glycogen-containing cells. However, PAS stain is not specific for myeloblasts and is not the correct answer.
* **Option B:** This option may refer to Sudan Black B stain, which is used to identify lipids in cells. However, Sudan Black B stain is not specific for myeloblasts and is not the correct answer.
* **Option C:** This option may refer to Alcian Blue stain, which is used to identify mucopolysaccharides in cells. However, Alcian Blue stain is not specific for myeloblasts and is not the correct answer.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that MPO stain is specific for myeloblasts and is a crucial diagnostic tool in the workup of AML. A positive MPO stain can help differentiate myeloblasts from other types of blasts, such as lymphoblasts, which are found in acute lymphoblastic leukemia (ALL).

**Correct Answer:**
MPO (Myeloperoxidase)