Internodes elongation is due to :

Options

A. Gibberellin
B. Auxin
C. Cytokinin
D. Abscisic acid

Answer

**Step-by-Step Solution:**

1. **Understanding Internodes**: Internodes are the segments of a plant stem between two nodes (the points where leaves are attached). Their elongation is crucial for the overall growth of the plant.

2. **Identifying the Hormones**: The question asks about the factors that contribute to the elongation of internodes. The options provided include different plant hormones.

3. **Analyzing the Options**:
- **Gibberellins**: This is a group of plant hormones that promote stem elongation. They are known to increase the length of the internodes, making them a key factor in this process. For instance, gibberellins help in increasing the length of grape stalks.
- **Oxygen**: This is not a hormone that promotes internode elongation. Instead, it is more associated with promoting root formation.
- **Cytokinins**: These hormones are primarily involved in promoting cell division and lateral bud growth, not specifically in the elongation of internodes.
- **Abscisic Acid**: This hormone is involved in various plant processes, including stress responses, but it does not promote internode elongation.

4. **Conclusion**: Based on the analysis, the hormone responsible for internode elongation is **Gibberellins**. Therefore, the correct answer is the first option.

**Final Answer**: Internodes elongation is due to Gibberellins.

---