Which one of the following is a growth regulator produced by plants ?

Options

A. Naphthalene acetic acid
B. Zeatin
C. 2,4-Dichlorophenoxyacetic acid
D. Benzyl aminopurine

Answer

To answer the question "Which one of the following is a growth regulator produced by plants?", we can follow these steps:

### Step 1: Understand the Options
We need to identify the options given in the question. The options include:
1. Naphthalene acetic acid (NAA)
2. 2,4-Dichlorophenoxyacetic acid (2,4-D)
3. G18
4. Benzyl aminopurine (BAP)

### Step 2: Identify the Nature of Each Compound
Next, we will analyze each compound to determine if it is synthetic or naturally produced by plants.

- **Naphthalene acetic acid (NAA)**: This is a synthetic auxin, which means it is not produced by plants but rather created artificially.

- **2,4-Dichlorophenoxyacetic acid (2,4-D)**: This is also a synthetic auxin and is used as a herbicide. It is not naturally occurring in plants.

- **G18**: This is a cytokinin that was first isolated from immature corn kernels. It is a natural growth regulator produced by plants.

- **Benzyl aminopurine (BAP)**: This is another synthetic cytokinin, which means it is artificially created and not produced by plants.

### Step 3: Conclusion
After analyzing the options, we find that G18 is the only growth regulator that is produced naturally by plants. Therefore, the correct answer to the question is **G18**.

### Final Answer
The growth regulator produced by plants is **G18**.

---