Which of the following is a class of fat-soluble vitamins?

The correct answer identifies vitamins A, D, E, and K as a class of fat-soluble vitamins. These vitamins are characterized by their ability to dissolve in fats and oils, which allows them to be stored in the body's fatty tissues and liver.

Each of these fat-soluble vitamins plays crucial roles in various biological functions. For instance, vitamin A is essential for vision and immune function, vitamin D is important for calcium absorption and bone health, vitamin E acts as an antioxidant, and vitamin K is necessary for blood clotting and bone metabolism. Because they can be stored in the body, it is also important to manage their intake, as excessive consumption can lead to toxicity.

In contrast, vitamin C is a water-soluble vitamin, meaning it dissolves in water and is not stored in the body in significant amounts. B vitamins, including B-12, are also part of the water-soluble group and play vital roles in energy metabolism and cellular function but do not share the storage characteristics of fat-soluble vitamins. Therefore, identifying vitamins A, D, E, and K as fat-soluble is key to understanding their unique properties and implications for human nutrition.