The element which is essential in nitrogen fixation is

Options

A. zinc
B. copper
C. molybdenum
D. boron

Explanation

**Step-by-Step Solution:**

1. **Understanding Nitrogen Fixation**: Nitrogen fixation is the process by which nitrogen (N2) in the atmosphere is converted into ammonia (NH3) or related compounds in soil and water. This process is essential for the growth of plants, as they cannot utilize atmospheric nitrogen directly.

2. **Identifying the Elements**: The question provides four options: Zinc, Copper, Molybdenum, and Boron. We need to evaluate the role of each in relation to nitrogen fixation.

3. **Analyzing Each Option**:
- **Zinc**: This element is primarily involved in the production of chlorophyll in plants. While it is essential for plant growth, it does not play a direct role in nitrogen fixation.
- **Copper**: Copper is important for photosynthesis, but like zinc, it does not directly contribute to the nitrogen fixation process.
- **Molybdenum**: This is a crucial micronutrient that is a component of the enzyme nitrogenase, which is directly involved in the nitrogen fixation process. It also plays a role in nitrate reductase, which is important for the assimilation of nitrate.
- **Boron**: Boron is essential for cell wall formation and stability in plants, but it does not have a direct role in nitrogen fixation.

4. **Conclusion**: Based on the analysis, Molybdenum (Option C) is the essential element required for nitrogen fixation due to its role in the nitrogenase enzyme.

5. **Final Answer**: The element which is essential in nitrogen fixation is **Molybdenum**.

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