**Core Concept**
Hodgkin's lymphoma is a type of lymphoma characterized by the presence of Reed-Sternberg cells, which is a distinct pathological feature of this disease. The etiology of Hodgkin's lymphoma involves a combination of genetic and environmental factors.

**Why the Correct Answer is Right**
Hodgkin's lymphoma is primarily caused by the Epstein-Barr virus (EBV), which is a member of the herpesvirus family. EBV infection can lead to the transformation of B lymphocytes, resulting in the formation of Reed-Sternberg cells. This viral infection triggers a series of molecular events, including the activation of oncogenes and the disruption of normal cellular pathways, ultimately leading to the development of Hodgkin's lymphoma. The association between EBV and Hodgkin's lymphoma is strongest in developing countries, where EBV infection is more common.

**Why Each Wrong Option is Incorrect**
**Option A:** While genetic factors, such as mutations in the tumor suppressor gene TP53, can contribute to the development of Hodgkin's lymphoma, they are not the primary cause of this disease.
**Option B:** Exposure to radiation and certain chemicals, such as pesticides and solvents, has been linked to an increased risk of developing Hodgkin's lymphoma, but these factors are not the primary cause of the disease.
**Option C:** Immunodeficiency disorders, such as HIV/AIDS, can increase the risk of developing Hodgkin's lymphoma, but they are not the primary cause of this disease.

**Clinical Pearl / High-Yield Fact**
The association between EBV and Hodgkin's lymphoma highlights the importance of viral infections in the development of cancer. Additionally, the presence of EBV in Reed-Sternberg cells can be detected using molecular techniques, such as PCR, which can aid in the diagnosis of Hodgkin's lymphoma.

**Correct Answer:** A. Epstein-Barr virus (EBV)