Growth promoter hormones are

Options

A. IAA, ABA and CK
B. IAA, GA and ABA
C. IAA, GA and CK
D. ABA, CK and GA.

Answer

### Step-by-Step Solution

1. **Understanding Plant Hormones**:
- Plant hormones are chemical substances that regulate various aspects of plant growth and development. They can be classified into two main categories: growth promoters and growth inhibitors.

2. **Identifying Growth Promoter Hormones**:
- Growth promoter hormones are those that stimulate growth and development in plants. Some of the key growth promoter hormones include:
- **Gibberellic Acid (GA)**: This hormone promotes stem elongation, seed germination, and flowering.
- **Indole Acetic Acid (IAA)**: This is a type of auxin that plays a crucial role in cell elongation, root formation, and response to light and gravity.
- **Cytokinins (CK)**: These hormones promote cell division and can delay aging in plants.

3. **Distinguishing Growth Inhibitors**:
- It is also important to recognize hormones that act as growth inhibitors. For example:
- **Abscisic Acid (ABA)**: This hormone generally inhibits growth and promotes seed dormancy.
- **Ethylene**: While it can promote fruit ripening, it also acts as a growth inhibitor in certain contexts.

4. **Conclusion**:
- Based on the understanding of plant hormones, the growth promoter hormones are:
- **Indole Acetic Acid (IAA)**
- **Gibberellic Acid (GA)**
- **Cytokinins (CK)**

5. **Final Answer**:
- Therefore, the correct answer to the question "Growth promoter hormones are" includes IAA, GA, and CK.