Steroids are

Options

A. Lipids
B. Proteins
C. Vitamins
D. Carbohydrate.

Answer

**Step-by-Step Solution:**

1. **Understanding Steroids**: Steroids are a class of organic compounds that are characterized by a specific molecular structure. They are biologically significant molecules that play various roles in the body.

2. **Role in Cell Membrane**: One of the primary functions of steroids is that they are components of cell membranes. They help maintain the fluidity and integrity of the membrane.

3. **Hormonal Function**: Many steroids act as hormones, which are signaling molecules that facilitate communication between different parts of the body. This includes hormones like testosterone and estrogen.

4. **Chemical Structure**: The chemical structure of steroids is distinctive. They are composed of four fused carbon rings. Three of these rings are hexagonal (six carbon atoms) and one is pentagonal (five carbon atoms).

5. **Hydrophobic Nature**: Steroids are hydrophobic, meaning they do not mix well with water. This property is typical of lipids, which are generally non-polar molecules.

6. **Classification**: Based on their structure and properties, steroids are classified as lipids. They share characteristics with other lipids, such as fats and oils.

7. **Example**: A common example of a steroid is cholesterol, which is vital for cell membrane structure and function.

8. **Conclusion**: Given the options provided (lipids, proteins, vitamins, carbohydrates), the correct classification of steroids is that they are lipids.

**Final Answer**: Steroids are lipids.

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