State the three characteristics of Acquired Immunity. List the different ways by which it can be attained by humans.

Explanation

### Step-by-Step Solution

**1. Define Acquired Immunity:**
- Acquired immunity is the type of immunity that is not present at birth but is developed over the course of an individual's life. It is specific to particular pathogens and involves the production of antibodies.

**2. State Three Characteristics of Acquired Immunity:**
- **Specificity:** Acquired immunity is pathogen-specific, meaning that it generates specific antibodies for specific pathogens. Different pathogens trigger the production of different antibodies.
- **Memory:** Acquired immunity has a memory component. Upon first exposure to a pathogen, the immune system creates a memory of that pathogen, allowing for a more rapid and robust response upon subsequent exposures.
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