**Core Concept**
Radioactive monoclonal antibodies are a type of targeted therapy used in cancer treatment. They are designed to specifically bind to cancer cells, delivering a radioactive payload that destroys the cells. This approach minimizes damage to healthy cells.

**Why the Correct Answer is Right**
The correct answer is Ibritumomab tiuxetan, a monoclonal antibody conjugated to the radioactive isotope Yttrium-90 (90Y). This radiopharmaceutical targets the CD20 antigen present on B-cell lymphoma cells. After binding to the cancer cells, the 90Y isotope emits beta radiation, causing cell death. Ibritumomab tiuxetan is used to treat non-Hodgkin's lymphoma, particularly relapsed or refractory disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** (no option provided) - There is no information to evaluate this choice.
* **Option B:** (no option provided) - Similarly, without more information, we cannot assess this option.
* **Option C:** (no option provided) - This option cannot be evaluated due to lack of information.
* **Option D:** (no option provided) - Without further details, we cannot determine why this option is incorrect.

**Clinical Pearl / High-Yield Fact**
When using radioactive monoclonal antibodies, it's essential to consider the radiation safety of both the patient and healthcare workers. This includes proper handling, storage, and disposal procedures to minimize exposure risks.

**Correct Answer: C. Ibritumomab tiuxetan.**