Which of the following is example of active immunity :-

Options

A. foetus receives antibodies from mother through placenta dring pregnancy.
B. colostrum secreted by mother during initial days of lacation has abundrant antibodies to protect the in fant.
C. Injecting the microbes deliberately during immunisation.
D. All of the above

Answer

To determine which of the following is an example of active immunity, we need to understand the concept of active immunity and how it differs from passive immunity.

### Step-by-Step Solution:

1. **Understand Active Immunity**: Active immunity occurs when the body produces its own antibodies in response to an antigen (foreign particle). This can happen naturally (through infection) or artificially (through vaccination).

2. **Identify the Options**: We need to analyze the given options to see which one represents active immunity.

- **Option 1**: "Fetus receives antibody from mother."
- In this case, the fetus receives antibodies (specifically IgG) directly from the mother through the placenta. This is an example of passive immunity because the fetus's immune system is not actively producing antibodies.

- **Option 2**: "Colostrum secreted by mother during initial days of lactation."
- Colostrum contains antibodies (specifically IgA) that are passed to the newborn. Again, this is passive immunity as the newborn is receiving pre-formed antibodies without producing them.

- **Option 3**: "Injecting the microbes deliberately during immunization."
- This option describes vaccination, where a person is exposed to a weakened or inactive form of a pathogen. The immune system responds by producing its own antibodies, which is the hallmark of active immunity.

3. **Conclusion**: After analyzing all options, we find that **Option 3** is the correct example of active immunity, as it involves the body actively producing antibodies in response to the introduced antigens.

### Final Answer:
**Option 3: Injecting the microbes deliberately during immunization is an example of active immunity.**

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