Explanation:
(a) Vitamins are organic substances which does not provide energy but are essential for healthy growth and proper functioning of body. Synthetically vitamins are not synthesized inside human body but they are essential part of our diet.
**NOTE**
Human body cannot synthesis Vitamin A, \(\mathrm{B}_{1}\), \(\mathrm{B}_{2}, \mathrm{~B}_{5}, \mathrm{~B}_{6}, \mathrm{~B}_{7}, \mathrm{~B}_{9}, \mathrm{~B}_{12}\) and K but are able to synthesize \(B_{3}\) and vitamin \(D\).