Explanation:

Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and multiple other biological effects. In humans, the most important compounds in this group are vitamin D3 and vitamin D2. The major natural source of the vitamin is synthesis of cholecalciferol in the skin from cholesterol through a chemical reaction that is dependent on sun exposure (specifically UVB radiation).[3][4] Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Only a few foods such as the flesh of fatty fish contain significant amounts of vitamin D and fish does not contain enough vitamin D to achieve optimal Vitamin D status without sunlight or supplements.