Hormone responsible for ageing is

Options

A. GA
B. IAA
C. ABA
D. Cytokinin.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the hormone responsible for aging in plants.

2. **Reviewing the Options**: The options provided are:
- Gibberellic acid
- Indole acetic acid
- Abscisic acid
- Cytokinin

3. **Analyzing Gibberellic Acid**:
- Gibberellic acid is known for promoting growth and elongation of cells.
- Since it primarily aids in growth rather than aging, this option is incorrect.

4. **Analyzing Indole Acetic Acid**:
- Indole acetic acid is involved in cell elongation and division, contributing to plant growth and development.
- It does not play a role in aging, making this option incorrect as well.

5. **Analyzing Abscisic Acid**:
- Abscisic acid is often referred to as the stress hormone.
- It is responsible for aging in plants and helps the plant respond to stress conditions such as drought and soil salinity.
- This option is correct.

6. **Analyzing Cytokinin**:
- Cytokinin is known for promoting cell division.
- It does not contribute to aging, so this option is also incorrect.

7. **Conclusion**: The hormone responsible for aging in plants is **Abscisic Acid**.