Classification of essential elements is :

Options

A. A quantitative feature
B. Based on the size of minerals
C. A qualitative feature
D. Based on the size of the plant

Answer

### Step-by-Step Solution:

1. **Understanding Essential Elements**: Essential elements are nutrients that plants require for their growth and development. They are classified based on the quantity needed by the plants.

2. **Classification of Essential Elements**: The essential elements are classified into two main categories:
- **Macronutrients**: These are the elements that plants need in larger quantities. Specifically, they are required in excess of 10 millimoles per kg of dry matter.
- **Micronutrients**: These are the elements that plants need in smaller quantities, which is less than 10 millimoles per kg of dry matter.

3. **Quantitative Feature**: The classification of these essential elements is based on the quantity required by the plants. Therefore, it is a quantitative feature. This means that the classification is determined by how much of each element is needed rather than the size of the minerals or the size of the plants.

4. **Conclusion**: The correct classification of essential elements is a quantitative feature based on the amount required by plants, distinguishing between macronutrients and micronutrients.