________classification systems were based on evolutionary relationships between various organisms.

Options

A. Natural
B. Artificial
C. Phylogenetic
D. both a and b

Explanation

To answer the question regarding the classification systems based on evolutionary relationships between various organisms, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Classification Systems**:
- Classification systems are methods used to categorize organisms based on their similarities and differences.

2. **Identifying Evolutionary Relationships**:
- Evolutionary relationships refer to how different organisms are related through common ancestry and evolutionary history.

3. **Recognizing Types of Classification**:
- There are various classification systems, such as artificial, natural, and phylogenetic classifications.

4. **Focusing on Phylogenetic Classification**:
- The phylogenetic classification system specifically organizes organisms based on their evolutionary history and relationships. It considers the evolutionary lineage and genetic connections among species.

5. **Concluding the Answer**:
- Therefore, the answer to the question is "phylogenetic classification."

### Final Answer:
The classification systems that were based on evolutionary relationships between various organisms are called **phylogenetic classification systems**.

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