Find the odd one (w.t.r critical element).

Options

A. Nitrogen
B. Potassium
C. Nickel
D. Phosphorus

Answer

To solve the question of finding the odd one with respect to critical elements, we will analyze each option based on their classification as macronutrients or micronutrients.

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Macronutrients**: These are essential elements required by plants in large amounts. They are critical for various metabolic processes.
- **Micronutrients**: These are essential elements required by plants in smaller amounts. They are often referred to as trace elements.

2. **Analyze the Options**:
- **Option A: Nitrogen**
- Classification: Macronutrient
- Conclusion: Nitrogen is a critical element.

- **Option B: Potassium**
- Classification: Macronutrient
- Conclusion: Potassium is also a critical element.

- **Option C: Nickel**
- Classification: Micronutrient
- Conclusion: Nickel is not considered a critical element in the same way as macronutrients are.

- **Option D: Phosphorus**
- Classification: Macronutrient
- Conclusion: Phosphorus is a critical element.

3. **Identify the Odd One Out**:
- From the analysis, we see that options A, B, and D (Nitrogen, Potassium, and Phosphorus) are all macronutrients and thus critical elements.
- Option C (Nickel) is a micronutrient and does not fit into the category of critical elements in the same way.

4. **Final Conclusion**:
- The odd one out with respect to critical elements is **Option C: Nickel**.