**Core Concept**
Auer rods are abnormal, needle-like inclusions found within the cytoplasm of myeloid blast cells in acute myeloid leukemia (AML). They are a hallmark of myeloid lineage cells and are often associated with specific subtypes of AML.

**Why the Correct Answer is Right**
Auer rods are numerous in AML subtypes with monocytic differentiation, particularly in acute monocytic leukemia (AMoL) and acute myelomonocytic leukemia (AMML). These inclusions are thought to represent abnormal, aggregated forms of primary or secondary granules within the myeloid cells. The presence of Auer rods in myeloid blasts is a diagnostic feature that helps distinguish AML from other types of acute leukemia.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Auer rods are not typically associated with acute lymphoblastic leukemia (ALL), which is a distinct entity characterized by lymphoid blast cells.
**Option B:** This option is incorrect because Auer rods are not a common feature of chronic myeloid leukemia (CML), which is a myeloproliferative disorder with a distinct clinical and pathological profile.
**Option C:** This option is incorrect because Auer rods are not a characteristic finding in acute promyelocytic leukemia (APL), which is a specific subtype of AML with a distinct genetic and clinical profile.

**Clinical Pearl / High-Yield Fact**
The presence of Auer rods in myeloid blasts is a key diagnostic feature of AML, particularly in subtypes with monocytic differentiation. This finding can help distinguish AML from other types of acute leukemia and guide further diagnostic and therapeutic efforts.

**Correct Answer:** C. Acute myelomonocytic leukemia (AMML).