Structural lipids of cell membrane are

Options

A. Simple lipid
B. Chromolipid
C. Phospholipid
D. Steroid.

Answer

### Step-by-Step Solution:

1. **Understanding Cell Membrane Composition**: The cell membrane is primarily composed of lipids, proteins, and carbohydrates. Among these, lipids play a crucial role in forming the structural framework of the membrane.

2. **Identifying Types of Lipids**: The question asks for the structural lipids of the cell membrane. The options provided are:
- Simple lipids
- Chromolipids
- Phospholipids
- Steroids

3. **Analyzing Each Option**:
- **Simple Lipids**: These are primarily triglycerides and do not have a significant role in forming the cell membrane structure.
- **Chromolipids**: These are lipids that contain pigments and are not structural components of the cell membrane.
- **Steroids**: While steroids are important for membrane fluidity, they do not serve as the primary structural lipids.
- **Phospholipids**: These are the main structural components of the cell membrane. They consist of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) fatty acid tails.

4. **Structure of Phospholipids**: Phospholipids have a phosphate group attached to the glycerol backbone, which makes the head hydrophilic. The two fatty acid tails are hydrophobic. This unique structure allows phospholipids to arrange themselves into a bilayer, with hydrophilic heads facing outward towards the water and hydrophobic tails facing inward, away from the water.

5. **Conclusion**: Based on the analysis, the correct answer to the question is **phospholipids**, as they are the structural lipids that form the cell membrane.

### Final Answer:
The structural lipids of the cell membrane are **phospholipids**.