DEFICIENCY.Due to its deficiency, calcium and phosphorus are not synthesized in the body.Rickets is a BONE disease that usually occurs in children.Weak BONES in children are called 'rickets'.The source of vitamin D is sunlight, the yellow part of the EGG, fish oil, milk, and butter.The chemical names of vitamins D and A are 'calciferol and retinal', respectively.The chemical names of vitamins B and K are 'thiamine and phylloquinone' respectively.Night BLINDNESS happens due to a lack of vitamin A.Scurvy is a disease that happens due to a deficiency of Vitamin C.Beriberi is a disease that happens due to a deficiency of Vitamin B.