Correct Answer: Ascorbic Acid

Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily functions, including:

$$\textbf{Antioxidant Function:}$$ It helps protect cells from damage caused by free radicals.

$$\textbf{Collagen Synthesis:}$$ It is crucial for the formation of collagen, a protein necessary for skin, cartilage, tendons, ligaments, and blood vessels.

$$\textbf{Immune Support:}$$ It supports the immune system by enhancing the body's natural defenses.

$$\textbf{Iron Absorption:}$$ It improves the absorption of non-heme iron from plant-based foods.

Among the given options, only ascorbic acid qualifies as a vitamin.