Which of the following damages WBC, bone-marrow and lymph nodes

Options

A. `I^131`
B. `Ca^40`
C. Caesium
D. `Sr^90`

Explanation

To determine which of the given options damages white blood cells (WBC), bone marrow, and lymph nodes, we can analyze each option provided.

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which substance damages WBC, bone marrow, and lymph nodes. We need to identify the correct option from the list provided.

2. **Analyze the Options**:
- **Option 1: Iodine-131**: This is a radioactive isotope of iodine. It is known to have biological effects, particularly on the thyroid gland, but it can also affect other tissues, including bone marrow and lymphatic tissues.
- **Option 2: Calcium-40**: This is a stable isotope of calcium and does not have radioactive properties. It is not known to cause damage to WBC, bone marrow, or lymph nodes.
- **Option 3: Calcium**: Similar to Calcium-40, regular calcium is essential for many biological functions and does not damage these tissues.
- **Option 4: Strontium-90**: This is a radioactive isotope that can replace calcium in bones and may have harmful effects on bone marrow and lymphatic tissues, potentially damaging WBC.

3. **Evaluate the Effects**:
- Iodine-131 is particularly known for its effects on the immune system and can cause damage to WBCs and bone marrow.
- Strontium-90 can also damage bone marrow, but it is less specific to WBCs compared to Iodine-131.

4. **Conclusion**: Based on the analysis, the most appropriate answer is **Iodine-131**, as it is specifically known to damage WBC, bone marrow, and lymph nodes.

### Final Answer:
**Iodine-131 damages WBC, bone marrow, and lymph nodes.**