All lipids are

Options

A. Composed of fatty acids
B. triglycerides
C. Insoluble in water
D. All the above

Answer

To answer the question "All lipids are," we need to analyze the given options one by one.

### Step-by-Step Solution:

1. **Understanding Lipids**:
- Lipids are a diverse group of hydrophobic organic molecules that are primarily composed of fatty acids. They include fats, oils, waxes, and steroids.

2. **Option 1: Composed of Fatty Acids**:
- This statement is correct. Most lipids are indeed composed of fatty acids. Fatty acids can be either saturated (solid at room temperature) or unsaturated (liquid at room temperature).

3. **Option 2: Triglycerides**:
- Triglycerides are a type of lipid. They consist of one glycerol molecule and three fatty acids. Therefore, while all triglycerides are lipids, not all lipids are triglycerides. This option is partially correct but does not encompass all lipids.

4. **Option 3: Insoluble in Water**:
- This statement is also correct. Lipids are generally hydrophobic and do not dissolve in water. This property is crucial for the formation of cell membranes, which are made up of lipid bilayers.

5. **Option 4: All the Above**:
- Since options 1 and 3 are correct and option 2 is a specific example of lipids, this option is also correct. Therefore, all the statements provided in the options are true regarding lipids.

### Conclusion:
The correct answer is **Option 4: All the above**.