`I^131` is used for the treatment of

Options

A. Skin cancer
B. Lung cancer
C. Thyroid cancer
D. Bone tumors

Answer

To solve the question regarding the use of Iodine-131 (I^131) in medical treatment, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Substance**: Recognize that Iodine-131 (I^131) is a radioisotope of iodine.

2. **Understand the Properties**: Note that I^131 has a half-life of approximately 8 days. This property is significant in medical applications as it allows for a controlled release of radiation over a period of time.

3. **Explore Medical Uses**: Research the medical applications of I^131. It is primarily used in the treatment of thyroid-related conditions, particularly hyperthyroidism and thyroid cancer.

4. **Evaluate the Options**:
- A. Skin cancer: I^131 is not typically used for skin cancer treatment.
- B. Lung cancer: I^131 is not used for lung cancer treatment.
- C. Thyroid cancer: I^131 is commonly used for treating thyroid cancer due to its ability to target thyroid cells.
- D. Bone marrow: I^131 is not used for treating bone marrow conditions.

5. **Select the Correct Answer**: Based on the evaluation, the correct answer is C. Thyroid cancer, as I^131 is specifically used for this type of cancer treatment.

### Final Answer:
The correct answer is **C. Thyroid cancer**.