Which of the following is a characteristic of triglycerides?

Triglycerides are indeed characterized by being composed of three fatty acids attached to a glycerol molecule. This structure is fundamental to their classification as a type of lipid. The glycerol serves as a backbone, while the three fatty acids contribute to the molecule's nonpolar nature, which is crucial for its functions within biological systems. This configuration allows triglycerides to store energy efficiently; they serve as a concentrated source of energy that can be metabolized by organisms.

The other options highlight misconceptions about triglycerides, as they do not fall under the category of steroids, are not water-soluble due to their hydrophobic character, and they function primarily as energy stores rather than not providing energy at all. Understanding the unique composition and properties of triglycerides is essential for grasping their roles in biology and metabolism.