Which is not a immunological technique?

Options

A. Antibiotic injection
B. Tetanus toxoid
C. Gamma-globulin
D. Smallpox vaccination

Answer

To determine which option is not an immunological technique, we will analyze each option provided:

1. **Antibiotic Injection**: Antibiotics are medications used to treat bacterial infections. They do not provide immunity; instead, they kill or inhibit the growth of bacteria. Therefore, this option is not an immunological technique.

2. **Tetanus Toxoid**: This is a vaccine that helps to provide immunity against tetanus. It is an immunological technique as it stimulates the immune system to produce a response.

3. **Gamma Globulin**: This is a preparation of antibodies that can provide passive immunity. It is used to prevent infections and is considered an immunological technique.

4. **Smallpox Vaccination**: This is a vaccine that provides immunity against smallpox. It is also an immunological technique as it helps the body to develop immunity.

Based on the analysis above, the correct answer is:

**Answer: Option A - Antibiotic Injection**

### Step-by-Step Solution:
1. **Identify the options**: List out the options provided in the question.
2. **Analyze each option**: Determine whether each option is an immunological technique or not.
- Antibiotic Injection: Not an immunological technique.
- Tetanus Toxoid: An immunological technique.
- Gamma Globulin: An immunological technique.
- Smallpox Vaccination: An immunological technique.
3. **Determine the correct answer**: Conclude which option does not belong to the category of immunological techniques.