Which one of the following has least similar characters ?

Options

A. family
B. Class
C. Genus
D. Species

Explanation

To determine which of the following taxonomic ranks has the least similar characters, we need to analyze the taxonomic hierarchy and the relationships between the ranks provided in the options: family, class, genus, and species.

### Step-by-Step Solution:

1. **Understand Taxonomic Hierarchy**: The taxonomic hierarchy is a system used to classify living organisms. It starts from broad categories and becomes more specific. The order from broadest to most specific is: Kingdom > Phylum > Class > Order > Family > Genus > Species.

2. **Identify the Options**: The options given are:
- Family
- Class
- Genus
- Species

3. **Analyze Similarity in Taxonomic Ranks**:
- **Species**: This is the most specific rank and includes organisms that are very similar to each other. Members of the same species share a high degree of similarity.
- **Genus**: A genus comprises multiple species that are closely related and share common characteristics, but they are still more diverse than species.
- **Family**: A family includes multiple genera (plural of genus) and has a broader range of characteristics than genus or species.
- **Class**: A class is a higher taxonomic rank that includes multiple orders. The organisms in a class can be quite different from each other, exhibiting a wide range of characteristics.

4. **Determine the Rank with Least Similar Characters**: Since the class encompasses a wide variety of organisms that can be quite different from one another, it represents the least similarity in characters compared to the other ranks. In contrast, species and genus have more closely related organisms.

5. **Conclusion**: Therefore, the taxonomic rank that has the least similar characters is **Class**.

### Final Answer:
The correct option is **Class**.

---