Which of the following don't occur naturally ?

Options

A. IAA
B. IBA
C. NAA
D. Both (A) and (B)

Answer

To solve the question "Which of the following don't occur naturally?" regarding plant growth hormones, we need to analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Hormones**: The question mentions three hormones: IAA, IBA, and NAA. We need to determine if each of these occurs naturally in plants.

2. **Understand Each Hormone**:
- **IAA (Indole-3-Acetic Acid)**: This is a well-known natural plant hormone that plays a crucial role in growth and development.
- **IBA (Indole-3-Butyric Acid)**: This is another natural auxin that is found in plants and is involved in root formation.
- **NAA (Naphthalene-Acetic Acid)**: This is a synthetic auxin that does not occur naturally in plants. It is often used in agriculture and horticulture to promote rooting and fruit development.

3. **Determine Which Hormone is Synthetic**: From the analysis:
- IAA and IBA are natural auxins.
- NAA is a synthetic auxin.

4. **Conclusion**: Since the question asks for the hormone that does not occur naturally, the correct answer is NAA (Naphthalene-Acetic Acid).

### Final Answer:
NAA (Naphthalene-Acetic Acid) does not occur naturally.

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