**Core Concept**
Chloroma is a type of extramedullary tumor that arises from the cells of the myeloid lineage, particularly from the granulocytic series. It is characterized by the abnormal accumulation of myeloid cells, which can lead to a range of systemic symptoms.

**Why the Correct Answer is Right**
The correct answer involves the pathophysiology of chloroma, which is a tumor that arises from the abnormal proliferation of myeloid cells. Chloroma is associated with a variety of conditions, including acute myeloid leukemia (AML), myeloproliferative neoplasms, and other myeloid disorders. The tumor cells in chloroma are derived from the granulocytic series and can produce leukocyte alkaline phosphatase (LAP), which is a key enzyme involved in the regulation of granulopoiesis.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because chloroma is not a tumor of the lymphoid lineage, which includes B cells and T cells.
* **Option B:** This option is incorrect because chloroma is not a tumor of the erythroid lineage, which includes red blood cells and their precursors.
* **Option C:** This option is incorrect because chloroma is not a tumor of the megakaryocytic lineage, which includes platelets and their precursors.

**Clinical Pearl / High-Yield Fact**
Chloroma is a systemic disease that can affect multiple organs, including the skin, bones, and central nervous system. It is often associated with a poor prognosis, particularly if left untreated.

**Correct Answer: D. Myeloid cells.**