A taxonomical key is used for

Options

A. Conserving various plant species
B. Identification of plants and animals
C. Studying geography of a plant
D. Nomenclature of plants and animals

Answer

### Step-by-Step Solution:

1. **Understanding the Taxonomical Key**:
A taxonomical key is a tool used in the field of biology for the identification of organisms. It provides a systematic way to categorize and identify various species based on their characteristics.

2. **Purpose of the Taxonomical Key**:
The primary purpose of a taxonomical key is to assist in the identification of both plants and animals. This is crucial for scientists and researchers when they encounter unknown or newly discovered organisms.

3. **How the Taxonomical Key Works**:
The taxonomical key operates on the principles of similarities and dissimilarities among organisms. By comparing the characteristics of an unknown organism with those of known organisms, the key helps in determining the classification of the unknown organism.

4. **Evaluating the Options**:
- **Option A**: Conserving various plant species - This is incorrect as a taxonomical key does not serve the purpose of conservation.
- **Option B**: Identification of plants and animals - This is correct as it directly relates to the function of a taxonomical key.
- **Option C**: Studying geography of a plant - This is incorrect as the key does not focus on geographical studies.
- **Option D**: Nomenclature of plants and animals - This is also incorrect as nomenclature refers to naming, which is different from identification.

5. **Conclusion**:
After evaluating the options, the correct answer is that a taxonomical key is used for the identification of plants and animals.

### Final Answer:
A taxonomical key is used for the identification of plants and animals.

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