Assertion: ELISA is based on the principle of antigen antibody interaction
Reason :Infection by pathogen can be detected by the presence of antigens or by detecting antibodies synthesized against
the pathogen

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion
B. It both Assertion & Reason are True but Reason is not a correct explanation of the Assetion
C. If Assertion is True but the Reason is False
D. If both Assertion & Reason are false

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "ELISA is based on the principle of antigen-antibody interaction."
- **Explanation**: ELISA (Enzyme-Linked Immunosorbent Assay) is a widely used laboratory technique that relies on the specific binding between antigens and antibodies. This interaction is fundamental to the detection of various substances, including pathogens.

2. **Understanding the Reason**: The reason provided is that "Infection by a pathogen can be detected by the presence of antigens or by detecting antibodies synthesized against the pathogen."
- **Explanation**: This statement is correct because infections can be diagnosed by identifying either the antigens produced by the pathogen or the antibodies produced by the immune system in response to the infection. ELISA can be used to detect both.

3. **Evaluating the Truth of Both Statements**:
- Both the assertion and the reason are true. ELISA indeed operates on the principle of antigen-antibody interaction, and it is also true that infections can be detected through the presence of antigens or antibodies.

4. **Determining the Relationship Between Assertion and Reason**:
- The reason provided accurately explains the assertion. The principle of antigen-antibody interaction is what allows ELISA to detect infections through the presence of antigens or antibodies.

5. **Conclusion**: Based on the evaluation, both the assertion and reason are true, and the reason correctly explains the assertion. Therefore, the answer is that both assertion and reason are true and the reason is the correct explanation of the assertion.

### Final Answer:
Both assertion and reason are true, and reason is the correct explanation of assertion.

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