Gibberellin is a

Options

A. Sterol
B. Vitamin
C. Suger
D. Protein.

Answer

### Step-by-Step Solution:

1. **Identify Gibberellin**: Begin by recognizing that gibberellin is a substance that plays a significant role in plant growth and development.

2. **Classify Gibberellin**: Determine the classification of gibberellin. It is categorized as a plant hormone, which means it is a chemical substance produced in plants that regulates growth and development.

3. **Chemical Structure**: Understand the chemical nature of gibberellin. It is classified as a dieterpenoid, which refers to its specific chemical structure.

4. **Synthesis Pathways**: Explore the synthesis of gibberellin. There are two main pathways for gibberellin synthesis:
- **Mevalonic Acid Dependent Pathway**: This pathway involves the synthesis of gibberellins through mevalonic acid.
- **Mevalonic Acid Independent Pathway**: This pathway operates without the involvement of mevalonic acid.

5. **Function of Pathways**: Recognize the significance of these pathways. The mevalonic acid dependent pathway is particularly important for the synthesis of steroids, which are crucial for various physiological processes in plants.

6. **Conclusion**: Based on the classification and synthesis of gibberellin, we can conclude that gibberellin is a plant hormone and specifically a dieterpenoid. Therefore, the correct answer to the question is that gibberellin is a plant hormone.

### Final Answer:
Gibberellin is a plant hormone and is classified as a dieterpenoid.

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