Which of the following vitamins is NOT fat-soluble?

Vitamin C is categorized as a water-soluble vitamin, which distinguishes it from the fat-soluble vitamins. Unlike vitamins A, D, and E, which can be stored in the body's fatty tissues and liver, Vitamin C dissolves in water and is readily excreted in urine. This means that the body cannot store large amounts of Vitamin C and requires regular intake through diet.

Fat-soluble vitamins, such as A, D, and E, play crucial roles in various bodily functions, including vision, immune health, and antioxidant activity, but they can accumulate to potentially toxic levels if consumed in excess. In contrast, the water-soluble nature of Vitamin C necessitates a consistent consumption to maintain adequate levels for its role in collagen synthesis, antioxidant protection, and enhancing iron absorption, among other functions. Thus, identifying Vitamin C as the vitamin that is not fat-soluble is based on this fundamental characteristic in how it interacts with the body compared to the fat-soluble vitamins.