Osteomalacia (softening of the bones in adults) and rickets (bone deformities in children) are caused by the deficiency of Vitamin D. Vitamin D plays a crucial role in the absorption of calcium and phosphorus, which are essential for maintaining healthy bone mineralization. On the other hand, deficiency of Vitamin A causes night blindness and xerophthalmia, deficiency of Vitamin K leads to an increase in blood clotting time, and deficiency of Vitamin E causes muscular weakness and increased fragility of RBCs.