The practical purpose of classification of living organisms is to

Options

A. (a) facilitate identification of unknown organisms
B. (b) explain the origin of living organisms.
C. (c) trace the evolution of living organisms
D. (d) name the living organisms

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the practical purpose of classifying living organisms. This means we need to identify what classification helps us achieve in a real-world context.

2. **Analyzing the Options**:
- **Option A**: Facilitate identification of unknown organisms.
- **Option B**: Explain the origin of living organisms.
- **Option C**: Trace the evolution of living organisms.
- **Option D**: Name the living organisms.

3. **Evaluating Each Option**:
- **Option A**: This option suggests that classification helps in identifying organisms that are not known. This is a practical application as it allows scientists and researchers to categorize and understand new species.
- **Option B**: While understanding the origin of organisms is important, it is more theoretical and not a direct practical application of classification.
- **Option C**: Tracing evolution is a significant aspect of biology, but it is more related to the study of phylogenetics rather than a practical purpose of classification.
- **Option D**: Naming organisms is a part of classification (nomenclature), but it is not the primary practical purpose.

4. **Conclusion**: The most appropriate answer is **Option A**, which states that the practical purpose of classification is to facilitate the identification of unknown organisms. This is essential given the vast number of species on Earth, estimated to be around 8.7 million.

### Final Answer:
The practical purpose of classification of living organisms is to **facilitate identification of unknown organisms** (Option A).

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