An order can be best defined as :-

Options

A. A group of related species and genera of different taxa
B. A group of related families which exhibit a few similar characters
C. A group of related classes which exhibit a few similarites
D. An assemblage of genera related to different classes

Answer

To define what an order is in biological classification, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Taxonomic Hierarchy**:
- Taxonomy is the science of classification of organisms. It has a hierarchical structure that includes several ranks: Kingdom, Phylum (or Division for plants), Class, Order, Family, Genus, and Species.

2. **Identifying the Rank of Order**:
- In this hierarchy, an order is situated above the family and below the class. This means that an order is composed of multiple families that share certain characteristics.

3. **Analyzing the Options**:
- **Option A**: "A group of related species and gender of different taxa" - This describes a family, not an order.
- **Option B**: "A group of related families which exhibit a few similar characters" - This is the correct definition of an order.
- **Option C**: "A group of related classes which exhibit a few similarities" - This describes a phylum or division, not an order.
- **Option D**: "An assemblage of genera related to different classes" - This also describes a family, not an order.

4. **Choosing the Correct Option**:
- Based on the analysis, the correct option that defines an order is **Option B**: "A group of related families which exhibit a few similar characters."

### Final Answer:
An order can be best defined as **a group of related families which exhibit a few similar characters**.

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