The chief constituents of cell membrances are :

Options

A. Simple triglycerides
B. Waxes
C. Phospholipids
D. Proteins

Explanation

### Step-by-Step Solution:

1. **Understanding Cell Membrane Composition**:
- The cell membrane is a crucial structure that separates the interior of the cell from the external environment. It is primarily composed of various biomolecules.

2. **Identifying Major Components**:
- The chief constituents of cell membranes are primarily **phospholipids**. These molecules are essential for the formation of the membrane structure.

3. **Phospholipid Structure**:
- Phospholipids consist of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails. This unique structure allows them to form a bilayer in an aqueous environment.

4. **Formation of the Phospholipid Bilayer**:
- When phospholipids are placed in water, they arrange themselves into a bilayer. The hydrophilic heads face outward towards the water, while the hydrophobic tails face inward, away from the water. This arrangement is crucial for maintaining the integrity and functionality of the cell membrane.

5. **Conclusion**:
- Therefore, the chief constituents of cell membranes are **phospholipids**, which form the fundamental structure of the membrane. Additionally, other components like proteins and cholesterol may also be present, but phospholipids are the primary building blocks.

### Final Answer:
The chief constituents of cell membranes are **phospholipids**.

---