**Core Concept**
Aplastic anemia is a rare, potentially life-threatening condition characterized by bone marrow failure, leading to pancytopenia, a reduction in the production of all three blood cell lines: red blood cells, white blood cells, and platelets.

**Why the Correct Answer is Right**
The patient's laboratory results show a hemoglobin (Hb) level of 8 gm%, indicating anemia; a white blood cell (WBC) count of 2000/mm^3, which is significantly below the normal range (typically 4,000-11,000/mm^3), indicating leukopenia; and a platelet count of 60,000/mm^3, which is lower than the normal range (typically 150,000-450,000/mm^3), indicating thrombocytopenia. This combination of cytopenias is characteristic of aplastic anemia, which results from a failure of the bone marrow to produce new blood cells. This condition is often caused by damage to the bone marrow stem cells, which can be due to various factors such as viral infections, radiation exposure, or certain medications.

**Why Each Wrong Option is Incorrect**
**Option A:** Thalassemia is a genetic disorder affecting hemoglobin production, leading to anemia, but it typically does not cause pancytopenia or affect WBC and platelet counts.

**Option B:** Sickle cell anemia is another genetic disorder affecting hemoglobin production, leading to anemia and other complications, but it is not associated with pancytopenia or a significant reduction in WBC and platelet counts.

**Option D:** Anemia of chronic disease, also known as anemia of inflammation, is a condition where anemia develops in response to chronic inflammation or infection. While it can cause anemia, it typically does not lead to pancytopenia or a significant reduction in WBC and platelet counts.

**Clinical Pearl / High-Yield Fact**
Aplastic anemia is a medical emergency that requires prompt treatment, often with immunosuppressive therapy or bone marrow transplantation. It is essential to recognize the symptoms and laboratory findings of aplastic anemia to provide timely and effective care.

**✓ Correct Answer: C. Aplastic anemia**