**Core Concept**
Angiosarcoma is a rare and aggressive type of cancer that arises from the endothelial cells lining the blood vessels. It can occur in various parts of the body, including the skin, liver, and lymph nodes. Understanding the risk factors for angiosarcoma is crucial for early diagnosis and treatment.

**Why the Correct Answer is Right**
Radiation exposure is a well-established risk factor for angiosarcoma. Ionizing radiation can cause genetic mutations in endothelial cells, leading to uncontrolled cell growth and tumor formation. This is particularly true in individuals who have received radiation therapy for other cancers. Additionally, certain genetic conditions such as Li-Fraumeni syndrome, which is associated with mutations in the TP53 gene, also increase the risk of developing angiosarcoma.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is not a valid risk factor for angiosarcoma. While certain chemical exposures have been linked to an increased risk of angiosarcoma, such as vinyl chloride monomer, this option does not specify a known risk factor.

**Option B:**
This option is not a risk factor for angiosarcoma. While certain environmental factors, such as exposure to arsenic, have been linked to an increased risk of various types of cancer, there is no established link between arsenic exposure and angiosarcoma.

**Option C:**
This option is not a risk factor for angiosarcoma. While certain viral infections, such as human papillomavirus (HPV), have been linked to an increased risk of certain types of cancer, there is no established link between viral infections and angiosarcoma.

**Option D:**
This option is not a risk factor for angiosarcoma. While certain genetic conditions, such as neurofibromatosis type 1, are associated with an increased risk of various types of cancer, there is no established link between neurofibromatosis type 1 and angiosarcoma.

**Clinical Pearl / High-Yield Fact**
Radiation-induced angiosarcoma often presents as a rapidly growing, ulcerated mass in the radiation field, and a high index of suspicion is necessary for early diagnosis and treatment.

**Correct Answer:** C. Radiation exposure