Classification of organisms on the basis of natural affinities `:`

Options

A. Was given by Theophrastus
B. Does not consider embryology and phytochemistry
C. Becomes more important when there is no supporting fossil evidence
D. Is more practical and also used in arrangement of herbaria sheets.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the classification of organisms based on natural affinities. This refers to a system of classification that groups organisms based on their natural relationships and characteristics.

2. **Identifying Key Concepts**: The key concepts to consider are:
- Natural classification
- Historical figures associated with classification (e.g., Theophrastus, Bentham, and Hooker)
- Types of characters used in classification (morphological, anatomical, embryological, etc.)

3. **Historical Context**: Theophrastus is known for proposing an artificial system of classification based on habitat, not natural affinities. This means the first option is incorrect.

4. **Analyzing the Options**:
- **Option 1**: Incorrect, as Theophrastus did not propose a natural classification system.
- **Option 2**: Incorrect, as natural classification does consider embryology and phytochemistry among other factors.
- **Option 3**: Incorrect, because natural classification is not specifically more important when there is no fossil evidence; it is a broader system that includes various types of data.
- **Option 4**: Correct, as natural classification is practical and widely used for organizing herbarium sheets, incorporating various characters such as morphological and anatomical traits.

5. **Conclusion**: The correct answer is that the classification based on natural affinities is more practical and is used in the arrangement of herbarium sheets.

### Final Answer:
The classification of organisms on the basis of natural affinities is more practical and widely used in the arrangement of herbarium sheets. Therefore, the correct option is the fourth one.

---