Which of the following provides immunity to digestive tract against antigen?

Options

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

Answer

To answer the question "Which of the following provides immunity to the digestive tract against antigens?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question is asking which immunoglobulin provides immunity specifically to the digestive tract against antigens.

2. **Identify the Options**: The options given are various types of immunoglobulins, including IgD, IgE, IgG, and IgA.

3. **Analyze Each Immunoglobulin**:
- **IgD**: This immunoglobulin primarily plays a role in the recognition of antigens by B-cells and activating them to secrete antibodies. It does not provide direct immunity to the digestive tract.
- **IgE**: IgE is mainly involved in mediating allergic responses and hypersensitivity reactions. It does not provide immunity to the digestive tract.
- **IgG**: This is the most abundant immunoglobulin in the body and is responsible for protecting body fluids and activating the complement system. However, it is not specifically targeted at the digestive tract.
- **IgA**: This immunoglobulin is found in mucosal areas, such as the digestive tract, and is present in secretions like saliva, tears, and breast milk. IgA plays a crucial role in mucosal immunity by providing protection against pathogens in the digestive tract.

4. **Select the Correct Answer**: Based on the analysis, IgA is the immunoglobulin that provides immunity to the digestive tract against antigens.

5. **Conclusion**: Therefore, the correct answer to the question is **IgA**.