The unit of classification containing concrete biological entities is

Options

A. taxon
B. Species
C. Category
D. order

Answer

To solve the question "The unit of classification containing concrete biological entities is," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Classification**:
- Classification in biology is the process of organizing living organisms into categories based on shared characteristics. This involves a hierarchical system where each level represents a rank or category.

2. **Identifying the Hierarchical Levels**:
- The main levels of biological classification include:
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
- Each of these levels is referred to as a "taxon" (plural: taxa).

3. **Defining Concrete Biological Entities**:
- Concrete biological entities refer to actual living organisms or groups of organisms that can be classified together.

4. **Recognizing the Unit of Classification**:
- The term that encompasses these categories, which contain concrete biological entities, is "taxon." A taxon can refer to any rank in the classification hierarchy, such as a kingdom, phylum, or species.

5. **Conclusion**:
- Therefore, the answer to the question is **Taxon**.

### Final Answer:
The unit of classification containing concrete biological entities is **Taxon**.