Vaccine against polio viruses is an example of

Options

A. auto-immunisation
B. Passive immunisation
C. active immunisation
D. simple immunisation.

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the classification of the vaccine against polioviruses. We need to identify which type of immunization the polio vaccine represents.

2. **Reviewing the Options**: The options given are:
- Autoimmunization
- Passive immunization
- Active immunization
- Simple immunization

3. **Analyzing Each Option**:
- **Autoimmunization**: This refers to a situation where the body's immune system mistakenly targets its own cells, producing antibodies against itself. This is not applicable to vaccines.
- **Passive Immunization**: This involves the administration of preformed antibodies to provide immediate immunity. This type does not involve the host's immune system actively producing antibodies.
- **Active Immunization**: This occurs when a vaccine containing an inactivated or attenuated form of a pathogen is introduced into the body. The immune system then responds by producing its own antibodies over time.
- **Simple Immunization**: This is a less specific term and generally refers to the introduction of an antigen to stimulate antibody production without specifying the mechanism.

4. **Identifying the Correct Answer**: The polio vaccine is designed to stimulate the immune system to produce antibodies against the poliovirus. Therefore, it falls under the category of **active immunization**.

5. **Conclusion**: The correct answer to the question is **active immunization**.