Thyroxine is

Options

A. Vitamin
B. Enzyme
C. Hormone
D. Excretory product

Answer

**Step-by-Step Solution:**

1. **Identify the Options**: The question asks what thyroxine is, and the options provided are vitamin, enzyme, hormone, or excretory product.

2. **Understand Thyroxine**: Thyroxine is a substance produced in the body. It is important to determine its classification.

3. **Locate the Source**: Thyroxine is secreted by the thyroid gland, which is a crucial point in identifying its nature.

4. **Function of Thyroxine**: Thyroxine plays a significant role in regulating metabolism. It affects how the body processes proteins, carbohydrates, and fats.

5. **Growth Regulation**: In addition to metabolism, thyroxine is also involved in regulating the growth of body tissues, indicating its importance in development and overall health.

6. **Synthesis Requirement**: The synthesis of thyroxine requires iodine. This is an essential element, and its deficiency can lead to various health issues.

7. **Conclusion**: Based on the above points, thyroxine is classified as a hormone due to its role in metabolic regulation and growth.

**Final Answer**: Thyroxine is a hormone.

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