Two species belonging to the same class must also belong to the same

Options

A. species
B. order
C. genus
D. phylum

Answer

To answer the question, "Two species belonging to the same class must also belong to the same...", we need to understand the hierarchy of biological classification, also known as taxonomy.

### Step-by-Step Solution:

1. **Understand Taxonomic Hierarchy**:
- Biological classification is organized in a hierarchical structure. The main taxonomic ranks, from broadest to most specific, are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

2. **Identify the Class**:
- If two species are in the same class, they share a higher taxonomic category. For example, if we consider mammals, all mammals belong to the class Mammalia.

3. **Determine Lower Taxonomic Ranks**:
- Since the class is a higher rank, any two species within the same class must also belong to the same or lower ranks. The ranks below class are Order, Family, Genus, and Species.

4. **Analyze the Options**:
- The options provided are:
- a) Order
- b) Genus
- c) Species
- d) Phylum
- Since the question specifies that the two species belong to the same class, they must also belong to the same Phylum (as Phylum is a higher rank than Class).

5. **Conclusion**:
- Therefore, the correct answer is "Phylum". Two species belonging to the same class must also belong to the same phylum.

### Final Answer:
**Phylum**