Immunoglobulin present in tears is

Options

A. IgD
B. IgG
C. IgA
D. IgM

Answer

To answer the question regarding the immunoglobulin present in tears, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four immunoglobulin options: IgD, IgG, IgA, and IgM.

2. **Evaluate IgD**:
- IgD is primarily found on the surface of B lymphocytes (a type of white blood cell).
- It plays a role in the immune response but is not found in tears.
- **Conclusion**: IgD is not the correct answer.

3. **Evaluate IgG**:
- IgG is the most abundant immunoglobulin in the blood and lymphatic fluid.
- It is involved in the body's immune response and helps in processes like clotting.
- **Conclusion**: IgG is not present in tears.

4. **Evaluate IgA**:
- IgA is known to be present in mucosal areas, such as tears, saliva, and breast milk.
- It plays a crucial role in mucosal immunity, protecting body surfaces exposed to pathogens.
- **Conclusion**: IgA is indeed present in tears.

5. **Evaluate IgM**:
- IgM is primarily found in the blood and is the first antibody produced in response to an infection.
- It is also present in the lining of the digestive tract.
- **Conclusion**: IgM is not found in tears.

6. **Final Answer**: After evaluating all options, the immunoglobulin present in tears is **IgA**.

### Summary:
The correct answer to the question "Immunoglobulin present in tears is" is **IgA**.