Immune response to first encounter with an antigen is called (

Options

A. Primary immune response
B. Secondary immune response
C. Anamnestic response
D. Clonal selection

Answer

**Step-by-Step Solution:**

1. **Understanding Immune Response**: The immune system is the body's defense mechanism against pathogens, including bacteria, viruses, and other foreign substances (antigens).

2. **First Encounter with an Antigen**: When the body encounters an antigen for the first time, it triggers a specific immune response. This initial response is crucial for the body to recognize and remember the antigen.

3. **Activation of the Immune System**: Upon the first exposure to an antigen, the immune system gets activated. This activation involves the recognition of the antigen by immune cells, leading to the production of specific antibodies and immune cells.

4. **Definition of Primary Immune Response**: The immune response that occurs during this first encounter with an antigen is referred to as the "primary immune response." It is characterized by a slower response time and the production of specific antibodies.

5. **Identifying the Correct Answer**: Among the options provided, the term that describes the immune response to the first encounter with an antigen is "primary immune response."

6. **Conclusion**: Therefore, the correct answer to the question is "primary immune response."

**Final Answer**: The immune response to the first encounter with an antigen is called the **Primary Immune Response**.

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