In a traditional system followed so far, in how many kingdoms the living world was grouped?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Traditional Classification System**: The traditional system of biological classification has been used for a long time to categorize living organisms based on their characteristics.

2. **Historical Background**: The classification was first proposed by the scientist Aristotle, who categorized organisms based on their morphological (structural) characteristics.

3. **Division into Two Main Groups**: Aristotle divided living organisms into two main groups:
- **Plants**: Organisms that can produce their own food (autotrophs).
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