Which hormone stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses?

Options

A. ABA
B. Cytokinin
C. `GA_(3)`
D. Auxin

Answer

To answer the question "Which hormone stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question is asking for a specific plant hormone that has two main functions: stimulating the closure of stomata and increasing the plant's tolerance to stress.

2. **Identify the Options**: The options provided are:
- A) Abscisic Acid (ABA)
- B) Cytokinin
- C) Gibberellic Acid
- D) Auxin

3. **Analyze Each Option**:
- **A) Abscisic Acid (ABA)**: This hormone is known to regulate various physiological processes in plants. It is primarily involved in stress responses, including drought stress, and is well-documented for its role in stimulating the closure of stomata to reduce water loss. It also increases the plant's tolerance to various stresses.
- **B) Cytokinin**: This hormone primarily promotes cell division and growth. It does not play a significant role in stomatal closure or stress tolerance.
- **C) Gibberellic Acid**: This hormone promotes growth and seed germination, acting in opposition to abscisic acid. It does not stimulate stomatal closure or enhance stress tolerance.
- **D) Auxin**: Auxins are involved in various growth processes, but they do not specifically stimulate stomatal closure or directly increase stress tolerance.

4. **Conclusion**: Based on the analysis, the hormone that stimulates the closure of stomata and increases tolerance to stress is **Abscisic Acid (ABA)**.

5. **Final Answer**: The correct answer is **A) Abscisic Acid (ABA)**.