Which of the following hormones is used in root formation on stem cutting?

Options

A. Kinetin
B. GA
C. ABA
D. IBA

Answer

To answer the question "Which of the following hormones is used in root formation on stem cutting?" we will analyze each option provided.

### Step 1: Understand the options
The options provided are:
1. Kinetin
2. GA (Gibberellic Acid)
3. ABA (Abscisic Acid)
4. IBA (Indole-3-butyric Acid)

### Step 2: Analyze each hormone
- **Kinetin**: This is a type of cytokinin, which primarily promotes cell division and shoot formation. It does not specifically promote root formation.

- **GA (Gibberellic Acid)**: This hormone is known for promoting stem elongation and seed germination. It is not involved in root formation.

- **ABA (Abscisic Acid)**: This hormone generally acts as a growth inhibitor and is involved in stress responses in plants. It does not promote root formation.

- **IBA (Indole-3-butyric Acid)**: This is an auxin, which is a class of hormones that promote root formation. IBA specifically stimulates root development in cuttings.

### Step 3: Conclusion
Based on the analysis of each hormone, the correct answer is **IBA (Indole-3-butyric Acid)**, as it is the hormone that promotes root formation on stem cuttings.

### Final Answer:
**IBA (Indole-3-butyric Acid)** is the hormone used in root formation on stem cutting.

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