Elongation and improvement of shape of apple fruit is carried out by which of the following growth regulator ?

Options

A. Auxin
B. GA
C. Ethylene
D. ABA

Answer

To determine which growth regulator is responsible for the elongation and improvement of the shape of apple fruit, we can analyze the options provided:

1. **Auxin**: This growth regulator is primarily involved in the elongation of roots and shoots. It also plays a role in preventing leaf and fruit drop, but it is not specifically known for improving the shape of fruits.

2. **Gibberellic Acid (GA)**: Gibberellic acid is known for its role in promoting growth and elongation in various plants. Its application can increase the size and shape of fruits, including apples. It is also known to enhance the yield of certain crops, such as barley and grapes.

3. **Ethylene**: Ethylene is a plant hormone that is primarily involved in the ripening of fruits. While it plays a crucial role in the maturation process, it does not directly contribute to the elongation or improvement of the shape of the fruit.

4. **Abscisic Acid**: This hormone is mainly involved in the plant's response to stress, particularly in relation to water availability. It does not play a significant role in fruit elongation or shape improvement.

Based on the analysis of these growth regulators, the correct answer to the question is:

**Gibberellic Acid (GA)** is responsible for the elongation and improvement of the shape of apple fruit.

### Step-by-Step Solution:
1. **Identify the Growth Regulators**: List the given options: Auxin, Gibberellic Acid (GA), Ethylene, and Abscisic Acid.
2. **Analyze Each Regulator**:
- Auxin: Involved in root and shoot elongation, prevents leaf/fruit drop.
- Gibberellic Acid: Promotes growth, increases size and shape of fruits.
- Ethylene: Involved in fruit ripening.
- Abscisic Acid: Responds to water stress.
3. **Determine the Role of Each Regulator**: Focus on which regulator is linked to fruit shape and size improvement.
4. **Conclude**: Based on the analysis, conclude that Gibberellic Acid is the correct answer.