Apical dominance is due to:

Options

A. Auxin
B. Cytokinin
C. Ethylene
D. Gibberellin

Answer

**Step-by-Step Solution:**

1. **Understanding Apical Dominance**:
- Apical dominance is a phenomenon in plants where the main stem (apex) grows more vigorously than the side stems (lateral buds). This results in the central stem being dominant over the lateral branches.

2. **Identifying the Role of Plant Hormones**:
- To determine the cause of apical dominance, we need to look at the plant hormones involved in this process.

3. **Analyzing the Options**:
- **Option A: Auxin**: This hormone is known to promote apical dominance by stimulating the growth of the apical bud while inhibiting the growth of lateral buds.
- **Option B: Cytokinins**: These hormones promote the growth of lateral buds, which is contrary to apical dominance.
- **Option C: Ethylene**: This hormone is primarily involved in fruit ripening and does not play a significant role in apical dominance.
- **Option D: Gibberellins**: These hormones are involved in seed germination and growth but do not influence apical dominance.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option A: Auxin**, as it is the hormone responsible for promoting apical dominance in plants.