Which of the following is an anti-gibberellin as well as a stress hormone?
(a) ABA
(b) CK
(c) NAAM
(d) 2, 4-D

Options

A. ABA
B. CK
C. NAAM
D. 2, 4-D

Answer

To solve the question "Which of the following is an anti-gibberellin as well as a stress hormone?", we will analyze each option provided and determine which one fits the criteria of being both an anti-gibberellin and a stress hormone.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Anti-Gibberellin**: This refers to a substance that inhibits the effects of gibberellins, which are plant hormones that promote growth and seed germination.
- **Stress Hormone**: This is a hormone that helps plants respond to stress conditions such as drought, salinity, or other environmental challenges.

2. **Analyzing Each Option**:
- **(a) ABA (Abscisic Acid)**:
- ABA is known to inhibit gibberellin activity, thus acting as an anti-gibberellin.
- It is also recognized as a stress hormone because it helps plants cope with stress conditions like drought and salinity.
- **(b) CK (Cytokinins)**:
- Cytokinins promote cell division and growth but do not act as anti-gibberellins or stress hormones.
- **(c) NAAM (Nicotinic Acid and Methyl Salicylate)**:
- NAAM is not commonly recognized as either an anti-gibberellin or a stress hormone.
- **(d) 2, 4-D (2,4-Dichlorophenoxyacetic acid)**:
- This is a synthetic auxin and is not known to function as an anti-gibberellin or a stress hormone.

3. **Conclusion**:
- After analyzing all the options, it is clear that **(a) ABA (Abscisic Acid)** is the only hormone that functions as both an anti-gibberellin and a stress hormone.

### Final Answer:
The correct answer is **(a) ABA**.

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