This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: vitamins, Subject name: Biochemistry
[{'content': 'Vitamin synthesised from amino acid is \nSelect and explain. \nA. Thiamine, B. Ribolflavin, C. Biotin, D. Niacin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Vitamin synthesized from amino acid niacin.Niacin, or nicotinic acid, is a substituted pyridine derivative. The biologically active coenzyme forms are nicotinamide adenine dinucleotide (NAD+) and its phosphorylated derivative, nicotinamide adenine dinucleotide phosphate.Reference: Lippincott Textbook of Biochemistry, fifth edition, pg no. 379', 'role': 'assistant'}]