Criterion of essentiality is applicable to:

Options

A. Only microelements
B. Only macronutrients
C. Both micro and macronutrients
D. All elments found is soil

Answer

### Step-by-Step Solution:

1. **Understanding Essential Nutrients**: Essential nutrients for plants are divided into two categories: macronutrients and micronutrients. Macronutrients include elements like calcium, magnesium, phosphorus, and potassium, while micronutrients include elements like zinc, nickel, chlorine, and boron.

2. **Criteria of Essentiality**: The criterion of essentiality states that a nutrient is considered essential if it is necessary for the normal growth and reproduction of plants. This means that without these nutrients, plants cannot complete their life cycle.

3. **Specificity of Requirement**: Each essential nutrient has a specific requirement for plants. This means that one nutrient cannot be replaced by another. For example, if a plant requires nitrogen, it cannot substitute it with phosphorus.

4. **Involvement in Metabolism**: Essential nutrients are directly involved in the metabolism of the plant. They play critical roles in various physiological processes necessary for growth and development.

5. **Conclusion**: Based on the criteria of essentiality, it is applicable to both microelements (micronutrients) and macroelements (macronutrients). Therefore, the correct answer to the question is that the criterion of essentiality is applicable to both micro and macronutrients.

### Final Answer:
The criterion of essentiality is applicable to both microelements (micronutrients) and macroelements (macronutrients).

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