Which group of substances includes steroids and triglycerides?

The correct answer is C, lipids. Lipids are a diverse group of organic compounds that are characterized primarily by their hydrophobic nature, meaning they do not mix well with water. This group includes a variety of substances, two of which are steroids and triglycerides.

Steroids are a type of lipid characterized by their four-ring carbon structure. They play vital roles in biological processes, including acting as hormones (such as testosterone and estrogen) and serving as components of cell membranes.

Triglycerides, on the other hand, are composed of glycerol and three fatty acids. They are the main form of fat stored in the body and serve as an energy reserve. They also play important roles in insulation and protecting vital organs.

Both steroids and triglycerides belong to the broader category of lipids because they share similar properties and functions related to energy storage, signaling, and structural components of cells.