Give the classification of vitamins.

(N/A) Vitamins are classified into two groups based on their solubility in water or fat.
$(i)$ Fat-soluble vitamins: Vitamins that are soluble in fats and oils but insoluble in water are placed in this group. These include vitamins $A, D, E,$ and $K$. They are stored in the liver and adipose (fat-storing) tissues.
$(ii)$ Water-soluble vitamins: $B$-group vitamins and vitamin $C$ are soluble in water,so they are grouped together. Water-soluble vitamins must be supplied regularly in the diet because they are readily excreted in urine and cannot be stored in our body (except for vitamin $B_{12}$).