What are lipid molecules primarily composed of?

Lipid molecules are primarily composed of one molecule of glycerol and three fatty acids when referring to triglycerides, which are the most common type of lipid in the body. Triglycerides serve as a concentrated energy source and provide insulation and protection for vital organs. The glycerol molecule acts as the backbone, to which the three fatty acids are attached through ester bonds. This structural combination plays a key role in the function and properties of fats, such as their ability to store energy and form membranes.

The other options do not accurately represent the standard composition of lipid molecules. For instance, glucose is a carbohydrate and does not typically form part of lipid structures. Similarly, the arrangement involving three glycerol molecules is not characteristic of any common lipids. Lastly, while phospholipids are important components of cell membranes, they are structurally different from triglycerides and do not consist of just one fatty acid and two phospholipids.