<prompt> Which of the following vitamin is metabolically produced by the body?BiotinVitamin KNiacinPyridoxine  <response>: Essential amino acid tryptophan can be conveed into Niacin B3 in our body 60 mg tryptophan 1 mg Niacin. As, it can be synthesised in the body by metabolism, strictly speaking, Niacin is not a Vitamin. 