The mineral elements most readily mobilised are all, expect

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which mineral element is not readily mobilized in plants. Mobilization refers to the ability of the plant to move nutrients from one part to another, especially from older tissues to younger ones.

2. **Identifying Readily Mobilized Elements**: Common mineral elements that are known to be readily mobilized in plants include:
- Phosphorus
- Sulfur
- Nitrogen
- Potassium

3. **Identifying Non-Mobilized Elements**: Some elements are structural components of plant tissues and cannot be easily moved. Calcium is one such element that is typically not mobilized within the plant.

4. **Analyzing the Options**: If we consider the options given in the question, we need to identify which one is calcium, as it is the exception among the listed elements.

5. **Conclusion**: Based on the information gathered, the mineral element that is not readily mobilized is calcium.

**Final Answer**: Calcium (Option 4)

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