The species confined to a particular region and not found elsewhere is termed as:

Options

A. Alien
B. Endemic
C. Rare
D. Keystone

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the term used to describe species that are confined to a particular region and are not found elsewhere.

2. **Analyzing the Options**:
- **Option 1: Alien Species**: These are species that are introduced to an area where they do not naturally occur. They are not confined to a specific region as they are from outside.
- **Option 2: Endemic Species**: These species are native to a specific region and are not found anywhere else in the world. This matches the definition provided in the question.
- **Option 3: Rare Species**: These species are uncommon but can exist in multiple regions. They do not fit the definition of being confined to a particular region.
- **Option 4: Keystone Species**: These species play a critical role in maintaining the structure of an ecosystem, but they can be found in various regions and are not limited to one specific area.

3. **Selecting the Correct Answer**: Based on the analysis, the correct term for species confined to a particular region and not found elsewhere is "Endemic Species."

4. **Final Answer**: Endemic Species.

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