Which of the following represents a characteristic of lipids?

Lipids are a diverse group of hydrophobic organic molecules that play various roles in biological systems, such as energy storage, insulation, and forming cell membranes. A key characteristic of many lipids, particularly fats and oils, is their composition. They are primarily formed from glycerol and fatty acids. The glycerol molecule serves as a backbone to which fatty acids are attached, creating structures such as triglycerides and phospholipids, which are crucial for building cellular membranes.

The other options refer to different classes of biomolecules. For instance, amino acids are the building blocks of proteins, while nucleotides are the building blocks of nucleic acids like DNA and RNA. Sugars are the primary components of carbohydrates, which are distinct from lipids. Thus, the presence of glycerol and fatty acids distinctly characterizes lipids.