Which one(s) is acidic in nature?

Options

A. Auxins
B. ABA
C. Both a and b
D. None of these

Answer

To determine which of the given options is acidic in nature, we need to analyze the options provided:

1. **Understanding the Options**:
- **Option 1: Auxin (often referred to as "oxen")** - Auxins are a class of plant hormones that promote growth. They are not typically classified as acidic.
- **Option 2: ABA (Abscisic Acid)** - ABA is a plant hormone that plays a role in stress responses and is indeed acidic in nature.
- **Option 3: Both (Auxin and ABA)** - This option suggests that both hormones are acidic.
- **Option 4: None of these** - This option suggests that neither hormone is acidic.

2. **Analyzing the Nature of Each Hormone**:
- **Auxin**: While auxins are important for plant growth, they are not classified as acidic. They have a neutral to slightly acidic pH, but they do not exhibit strong acidic properties.
- **ABA**: Abscisic acid is a well-known plant hormone that is indeed acidic. It plays a significant role in plant responses to stress and is involved in processes like stomatal closure.

3. **Conclusion**:
- Based on the analysis, ABA is the only hormone among the options that is acidic in nature. Auxin does not qualify as acidic. Therefore, the correct answer to the question "Which one(s) is acidic in nature?" is **Option 2: ABA**.

### Final Answer:
**ABA (Abscisic Acid) is acidic in nature.**