Apical dominance is caused due to action of

Options

A. auxins
B. gibberellins
C. cytokinins
D. abscissic acid

Answer

### Step-by-Step Solution:

1. **Understanding Apical Dominance**: Apical dominance refers to the phenomenon where the main central stem or apical bud of a plant inhibits the growth of lateral or axillary buds. This is a common characteristic in higher plants.

2. **Identifying the Hormones**: Several plant hormones are involved in growth and development, including auxins, gibberellins, cytokinins, and abscisic acid. Each of these hormones has specific roles in plant growth.

3. **Role of Auxins**: Among these hormones, auxins are primarily responsible for apical dominance. They promote the growth of the apical bud while inhibiting the growth of lateral buds.

4. **Effects of Auxins**: Auxins not only regulate apical dominance but also play a role in other processes such as:
- Inducing parthenocarpy (fruit development without fertilization).
- Controlling xylem differentiation.
- Assisting in cell division.

5. **Examples of Auxins**: Natural auxins include Indole-3-acetic acid (IAA) and Indole-butyric acid (IBA). Synthetic auxins include 2,4-D (2,4-dichlorophenoxyacetic acid).

6. **Exclusion of Other Hormones**:
- Gibberellins are primarily involved in promoting internodal elongation.
- Cytokinins are responsible for promoting cell division.
- Abscisic acid functions mainly as a stress hormone, regulating processes like senescence and dormancy.

7. **Conclusion**: Based on the above information, the hormone responsible for apical dominance is auxin.

### Final Answer:
**Apical dominance is caused due to the action of auxins.**

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