systematics is

Options

A. the science based on characterization, identification, and nomenclature of organism
B. the science which deals with diversity of organisms and their comparative and evolutionary relationship among them
C. derived from Greek word 'systema'
D. the science which is best on observable morphological characters.

Answer

**Step-by-Step Solution:**

1. **Understanding Systematics**: Begin by defining what systematics is. Systematics is the branch of science that deals with the diversity of organisms and their evolutionary relationships. It encompasses the study of how different organisms are related to one another through evolution.

2. **Analyzing the Options**: The question provides several options to choose from regarding the definition of systematics. We need to evaluate each option carefully.

3. **Evaluating Option 1**: The first option states that systematics is the science based on characterization, identification, and nomenclature of organisms. This description aligns more closely with taxonomy, which is a different branch of biology focused on naming and classifying organisms. Therefore, this option is incorrect.

4. **Evaluating Option 2**: The second option states that systematics is the science that deals with the diversity of organisms and their comparative and evolutionary relationships. This accurately describes systematics as discussed earlier. Thus, this option is correct.

5. **Evaluating Option 3**: The third option claims that systematics is derived from the Greek word "Systema." However, systematics actually derives from the Latin word "Systema," which means systematic arrangement. Therefore, this option is incorrect.

6. **Evaluating Option 4**: The fourth option suggests that systematics is based on observable morphological characters. This description is more aligned with morphology, which studies the form and structure of organisms. Hence, this option is also incorrect.

7. **Conclusion**: After evaluating all the options, the only correct definition of systematics is provided in option 2.

**Final Answer**: The correct definition of systematics is the science which deals with the diversity of organisms and their comparative and evolutionary relationships among them (Option 2).

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