Which of the following hormones is not a polypeptide?

Options

A. LH
B. FSH
C. Insulin
D. Thyroxine

Explanation

To determine which of the following hormones is not a polypeptide, we need to analyze each option provided: LH, FSH, Insulin, and Thyroxine.

### Step-by-Step Solution:

1. **Identify the Hormones**: The hormones listed are:
- LH (Luteinizing Hormone)
- FSH (Follicle-Stimulating Hormone)
- Insulin
- Thyroxine

2. **Classify the Hormones**: We need to classify these hormones based on their structure:
- **LH**: Luteinizing Hormone is a glycoprotein hormone, which is a type of polypeptide.
- **FSH**: Follicle-Stimulating Hormone is also a glycoprotein hormone, thus classified as a polypeptide.
- **Insulin**: Insulin is a peptide hormone made up of amino acids, hence it is also a polypeptide.
- **Thyroxine**: Thyroxine (T4) is an iodothyronine hormone, derived from the amino acid tyrosine but is not classified as a polypeptide.

3. **Conclusion**: Among the hormones listed, LH, FSH, and Insulin are all polypeptide hormones, while Thyroxine is not. Therefore, the hormone that is not a polypeptide is Thyroxine.

4. **Final Answer**: The correct answer is **Thyroxine** (Option 4).