…………….... classified animals into two groups, those which have red blood and those that did not.

Options

A. Aristotle
B. Theophrastus
C. Linnaeus
D. Whittaker

Answer

To solve the question, we need to identify who classified animals into two groups based on the presence or absence of red blood cells.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about a classification system that divides animals into two groups: those with red blood and those without.

2. **Identifying Key Historical Figures**: We need to recall significant contributors to biological classification. Key figures include Aristotle, Theophrastus, Linnaeus, and Whittaker.

3. **Reviewing Aristotle's Contributions**: Aristotle is known for his early classification of animals. He categorized them based on observable characteristics, including the presence of blood.

4. **Defining the Two Groups**: Aristotle classified animals into two main groups:
- **Enema**: Animals that have blood (red blood).
- **Anema**: Animals that do not have blood (these are typically invertebrates).

5. **Evaluating Other Options**:
- **Theophrastus**: Known for plant classification, not specifically for blood classification in animals.
- **Linnaeus**: Developed the binomial nomenclature and two-kingdom classification but did not classify based on blood.
- **Whittaker**: Proposed the five-kingdom system in 1969, which is more complex and does not focus on blood classification.

6. **Conclusion**: Based on the historical context and classification methods, the correct answer is Aristotle.

### Final Answer:
Aristotle classified animals into two groups based on the presence or absence of red blood cells.

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