Primary deficiency in plants is caused by all, except,

Options

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

Answer

To solve the question regarding primary deficiency in plants, we need to identify which element is not classified as a primary nutrient. Let's break it down step by step.

### Step-by-Step Solution:

1. **Understand Primary Nutrients**:
- Primary nutrients are essential elements that plants require in larger quantities. These include nitrogen (N), phosphorus (P), and potassium (K).

2. **Identify Macronutrients and Micronutrients**:
- Macronutrients are needed in larger amounts (like N, P, K), while micronutrients are required in smaller amounts (like iron, manganese, zinc).

3. **Recognize the Role of Each Nutrient**:
- **Nitrogen (N)**: Vital for amino acids, proteins, and nucleic acids. Its deficiency leads to stunted growth and yellowing of leaves.
- **Phosphorus (P)**: Important for energy transfer (ATP) and nucleic acids. Deficiency can cause poor root development and dark green or purplish leaves.
- **Potassium (K)**: Crucial for enzyme activation and osmoregulation. Deficiency results in weak stems and leaf curling.
- **Sulfur (S)**: While important, it is generally classified as a secondary nutrient rather than a primary nutrient. It is involved in protein synthesis and enzyme function but is not needed in the same large quantities as the primary nutrients.

4. **Evaluate the Options**:
- Given the context of the question, we need to determine which element does not cause primary deficiency. The options typically include nitrogen, phosphorus, potassium, and sulfur.

5. **Conclusion**:
- Since nitrogen, phosphorus, and potassium are all primary nutrients, the element that does not cause a primary deficiency is **sulfur**.

### Final Answer:
The correct answer is **sulfur**.

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