Which vitamin is often associated with metabolic functions in the body?

The correct answer, vitamin B12, is essential for various metabolic functions in the body. It plays a crucial role in the formation of red blood cells, nerve cell health, and DNA synthesis. Vitamin B12 is important for energy metabolism, as it helps convert carbohydrates into glucose, which the body uses for energy. Additionally, it is key in the metabolism of fatty acids and amino acids, influencing overall metabolic activity.

Other vitamins listed have different main functions; for instance, vitamin A is primarily important for vision and immune function, while vitamin C is well-known for its role in the immune system and collagen synthesis, and vitamin D is mainly associated with calcium absorption and bone health. Thus, vitamin B12 stands out for its direct involvement in metabolic processes.