Abscission of leaves and flowers is promoted

Options

A. ethylene
B. abscisic acid
C. auxin
D. cytokinin

Answer

### Step-by-Step Solution:

1. **Understanding Abscission**: Abscission refers to the process by which leaves, flowers, or fruits detach from a plant. This process is crucial for the plant's life cycle and can be influenced by various hormones.

2. **Identifying Plant Hormones**: The question lists four plant hormones: ethylene, abscisic acid, auxin, and cytokinin. It's important to categorize these hormones into those that promote growth and those that inhibit or regulate processes like abscission.

3. **Hormonal Functions**:
- **Ethylene**: This hormone is known for its role in fruit ripening and promoting senescence (aging) in plants. It is also directly involved in the abscission process.
- **Abscisic Acid (ABA)**: This hormone is primarily a stress hormone that helps in closing stomata and inducing dormancy. It does not promote abscission.
- **Auxin**: Generally promotes growth and development in plants and inhibits abscission.
- **Cytokinin**: Promotes cell division and growth, also inhibiting abscission.

4. **Conclusion**: Based on the functions of these hormones, ethylene is identified as the hormone that promotes the abscission of leaves and flowers. Therefore, the correct answer to the question is ethylene.

### Final Answer:
The plant hormone that promotes the abscission of leaves and flowers is **ethylene**.

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