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': 'Which of the following is strictly not a vitamin? \nSelect and explain. \nA. Thiamine, B. Riboflavin, C. Niacin, D. Cobalamin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: NIACIN IS NOT STRICTLY A VITAMIN Niacin was discovered as a nutrient during studies of pellagra. It is not strictly a vitamin since it can be synthesized in the body from the essential amino acid Reference: Harper; 30th edition; Page no: 556', 'role': 'assistant'}]