Hormone antagonistic ABA is

Options

A. Gibberellin
B. Auxin
C. Ethylene
D. Cytokinin.

Answer

### Step-by-Step Solution:

1. **Understanding ABA (Abscisic Acid)**:
- Abscisic acid (ABA) is a plant hormone known for its role in inhibiting growth and promoting dormancy. It is often referred to as an antagonistic hormone because it counteracts the effects of growth-promoting hormones.

2. **Defining Antagonistic Hormones**:
- Antagonistic hormones are those that work in opposition to each other to maintain homeostasis in the plant. They help regulate various physiological processes by balancing each other's effects.

3. **Identifying the Options**:
- The options provided are:
- A) Javelin
- B) Auxin
- C) Ethylene
- D) Cytokinin

4. **Analyzing Each Option**:
- **Auxin**: This hormone promotes cell growth and elongation, which is opposite to the function of ABA. Therefore, it is not antagonistic to ABA.
- **Ethylene**: This hormone regulates growth and senescence (aging) in plants. It also does not serve as an antagonist to ABA.
- **Cytokinin**: This hormone stimulates cell division and promotes shoot growth. Like auxin and ethylene, it does not counteract ABA.
- **Javelin (Gibberellin)**: Gibberellin is known to promote growth, seed germination, and flowering. It acts in opposition to ABA, which promotes dormancy and inhibits growth.

5. **Conclusion**:
- The correct answer is **Javelin (Gibberellin)**, as it acts antagonistically to ABA by promoting growth and breaking seed dormancy.