The substance that triggers the fall of mature leaves and fruits from plants is due to

Options

A. Auxin
B. gibberellin
C. abscisic acid
D. cytokinin

Explanation

**Step-by-Step Solution:**

1. **Identify the Question:** The question asks for the substance that triggers the fall of mature leaves and fruits from plants.

2. **Understand the Options:** The options provided are:
- Auxin
- Gibberellin
- Abscisic acid
- Cytokinin

3. **Classify the Hormones:**
- Auxin, Gibberellin, and Cytokinin are known as growth-promoting phytohormones. They are involved in promoting growth and development in plants.
- Abscisic acid is different; it is known to inhibit growth and is associated with stress responses in plants.

4. **Function of Abscisic Acid:**
- Abscisic acid plays a crucial role in plant processes such as inducing dormancy in seeds and triggering the formation of the abscission layer, which is responsible for the separation of leaves and fruits from the plant.

5. **Formation of Abscission Layer:**
- The abscission layer is a layer of cells that forms at the base of the leaf or fruit stem, which disconnects the living tissue of the leaf or fruit from the rest of the plant.

6. **Conclusion:** Based on the functions of the hormones, the substance that triggers the fall of mature leaves and fruits is **Abscisic acid**.

7. **Final Answer:** The correct answer is **Abscisic acid**.

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