Assertion : The specific diversity present in a given community or habitat is referred to as alpha diversity.
Reason : Alpha diversity is usually expressed by species richness and species evenness in that community or habitat.

Options

A. a) If both assertion and reason are true and reason is the correct explanation of assertion.
B. b) If both assertion and reason are true but reason is not the correct explanation of assertion.
C. c) If assertion is true but reason is false.
D. d) If both assertion and reason are false.

Explanation

To solve the question, we will evaluate the assertion and reason provided and determine their validity and relationship.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "the specific diversity present in a given community or habitat is referred to as alpha diversity."
- Alpha diversity indeed refers to the diversity of species within a specific community or habitat. It is a measure of the number of different species (species richness) and their relative abundance (species evenness) in that particular area.

2. **Evaluating the Reason**:
- The reason states that "alpha diversity is usually expressed by species richness and species evenness in that community or habitat."
- This statement is correct. Alpha diversity is quantified using two main components:
- **Species Richness**: The total number of different species present in the community.
- **Species Evenness**: The relative abundance of each species, indicating how evenly the individuals are distributed among the species.

3. **Conclusion**:
- Since both the assertion and the reason are true, and the reason accurately explains the assertion, we can conclude that both statements are correct and that the reason is a correct explanation of the assertion.

4. **Choosing the Correct Option**:
- Based on the evaluation, the correct option is:
- **Option A**: If both assertion and reason are true and reason is correct explanation of assertion.

### Final Answer:
The correct answer is **Option A**.

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