Which one of the following is not a micronutrient

Options

A. Boron
B. Molybdenum
C. Magnesium
D. Zinc

Answer

To determine which of the following is not a micronutrient, we need to understand the definitions and classifications of nutrients in plants.

### Step-by-Step Solution:

1. **Understand Micronutrients**: Micronutrients are essential elements required by plants in very small quantities. They play crucial roles in various physiological functions.

2. **Identify the Options**: The options given are:
- A) Boron
- B) Molybdenum
- C) Magnesium
- D) Zinc

3. **Classify Each Option**:
- **Boron**: This is a micronutrient essential for plant growth and development.
- **Molybdenum**: This is also a micronutrient, important for nitrogen fixation and enzyme function.
- **Magnesium**: This is classified as a macronutrient, as it is required in larger amounts compared to micronutrients. It is vital for photosynthesis as it is a central component of chlorophyll.
- **Zinc**: This is a micronutrient that is important for various enzymatic reactions in plants.

4. **Conclusion**: Among the options provided, Magnesium (option C) is not a micronutrient; it is a macronutrient.

### Final Answer:
**C) Magnesium** is not a micronutrient.

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