A natural system of classification is

Options

A. 2- dimensional
B. A horizontal system
C. Based on typological species concept
D. ( Both (1) and (2)

Explanation

### Step-by-Step Solution:

1. **Understanding Natural Classification**: A natural system of classification is a method used to categorize organisms based on shared characteristics. It emphasizes the relationships and similarities among organisms rather than just their physical traits.

2. **Key Properties**: The natural system of classification utilizes various properties such as:
- Morphology (the study of form and structure)
- Cytology (the study of cells)
- Phytochemistry (the study of the chemicals derived from plants)
- Embryology (the study of embryos and their development)
- Anatomy (the study of the structure of organisms)

3. **Purpose of Classification**: The main goal of this classification system is to find similarities and dissimilarities among organisms. It helps in understanding the evolutionary relationships and the homology among diverse organisms.

4. **Two-Dimensional Nature**: The natural system of classification is described as two-dimensional. This means it can incorporate data from various sources and is flexible enough to adapt to new information as it becomes available.

5. **Horizontal System**: This classification is also referred to as a horizontal system because it organizes organisms based on a wide range of data rather than a strict hierarchy.

6. **Typological Species Concept**: The typological species concept, which classifies organisms based on fixed traits, is not the basis of the natural system of classification. Instead, the natural classification focuses on a broader range of characteristics.

7. **Conclusion**: Based on the analysis, the first two statements about the natural system of classification being two-dimensional and horizontal are correct. The statement regarding it being based on the typological species concept is incorrect. Therefore, the correct answer to the question is that both the first and second statements are true.

### Final Answer:
The correct answer is: **Both 1 and 2**.

---