Which hormone is used to initiate flowering and synchronising fruit set in pineapple?

Options

A. `C_2 H_2`
B. `C_2 H_4`
C. `GA_3`
D. `IA A`

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the specific hormone that is responsible for initiating flowering and synchronizing fruit set in pineapple plants.

2. **Identifying the Options**: The options provided are:
- C2H2 (Ethylene)
- C2H4 (Ethylene)
- GA3 (Gibberellic Acid)
- IAA (Indole-3-acetic acid)

3. **Analyzing the Hormones**:
- **C2H2 (Ethylene)**: This is a gaseous plant hormone known for its role in fruit ripening, flowering, and the regulation of various developmental processes.
- **C2H4 (Ethylene)**: This is also ethylene, represented in a different chemical notation. It is the same as C2H2.
- **GA3 (Gibberellic Acid)**: This hormone is primarily involved in promoting stem elongation, seed germination, and flowering in some plants but is not specifically known for pineapple.
- **IAA (Indole-3-acetic acid)**: This is a form of auxin, which is involved in cell elongation and growth but does not specifically trigger flowering in pineapple.

4. **Conclusion**: Based on the analysis, ethylene (C2H2 or C2H4) is the hormone that initiates flowering and synchronizes fruit set in pineapple.

5. **Final Answer**: The hormone used to initiate flowering and synchronize fruit set in pineapple is **Ethylene (C2H4)**.