**Core Concept**
Radioactive iodine and thyroid hormone analogs play a crucial role in the treatment of thyroid carcinoma. The therapeutic effect is achieved by selectively targeting the malignant thyroid cells that avidly take up iodine.

**Why the Correct Answer is Right**
The correct answer is a radioactive iodine compound that is used to destroy thyroid tissue, including cancer cells. **Radioiodine (I-131)** selectively targets and eliminates the malignant thyroid cells through a process called apoptosis. This treatment is particularly effective for well-differentiated thyroid cancers such as papillary and follicular thyroid carcinomas.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because **Methimazole** is a medication used to treat hyperthyroidism, but it is not used in the treatment of thyroid carcinoma.
**Option B:** This option is incorrect because **Levothyroxine** is a synthetic form of thyroid hormone used to treat hypothyroidism, not thyroid carcinoma.
**Option C:** This option is incorrect because **Lithium** is a medication used to treat bipolar disorder and is not indicated in the treatment of thyroid carcinoma.

**Clinical Pearl / High-Yield Fact**
When treating thyroid carcinoma with radioactive iodine, it is essential to ensure that the patient is euthyroid and has normal kidney function to minimize the risk of adverse effects.

**Correct Answer: C. Lithium**