Vitamin D is a fat-soluble vitamin that is produced in the skin due to the exposure of UV radiation on the skin. When the UV radiation penetrates the skin the provitamin D3 is converted into previtamin D3. Then this previtamin D3 gets isomerize to vitamin D3 which is natural form of the vitamin D.
This vitamin D is important for normal bone growth and its function. Vitamin D helps our bone to become strong by helping bone to absorb calcium from the food. It protects osteoporosis in older adults. Therefore the correct answer is vitamin D.