Seed dormancy can be broken by the following combination of chemicals

Options

A. `GA_(3)`, IAA, ABA
B. `KNO_(3), GA_(3)` and ethylene chlorohydrin
C. NAA, 2, 4, 5-T and IAA
D. ABA, BAP and `GA_(3)`

Answer

### Step-by-Step Solution:

1. **Understanding Seed Dormancy**: Seed dormancy refers to a state in which seeds are unable to germinate despite favorable conditions. This dormancy is often due to a hard seed coat or other physiological factors.

2. **Identifying Chemicals Involved**: The question asks for a combination of chemicals that can break seed dormancy. Common chemicals involved in seed dormancy include:
- Abscisic Acid (ABA)
- Auxins (IAA)
- Gibberellins (GA3)
- Potassium Nitrate (KNO3)
- Ethylene

3. **Analyzing Each Chemical**:
- **Abscisic Acid (ABA)**: This hormone promotes seed dormancy. Therefore, it is not useful for breaking dormancy.
- **Auxins (IAA)**: Auxins also promote seed dormancy, making them ineffective for breaking dormancy.
- **Gibberellins (GA3)**: This hormone is known to promote germination and break dormancy, making it a suitable candidate.
- **Potassium Nitrate (KNO3)**: KNO3 is effective in breaking seed dormancy by softening the seed coat, allowing for germination.
- **Ethylene**: This hormone can also help in breaking dormancy by promoting ripening and germination processes.

4. **Selecting the Correct Combination**: From the analysis, the combination of chemicals that can effectively break seed dormancy includes:
- Gibberellins (GA3)
- Potassium Nitrate (KNO3)
- Ethylene

5. **Final Answer**: The correct combination of chemicals that can break seed dormancy is **KNO3, GA3, and Ethylene**.