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 vitamins contain sulfur in its structure? \nSelect and explain. \nA. Thiamine, B. Riboflavin, C. Folic acid, D. Niacin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Thiamine contains Sulphur in its structure. Structure of Thiamine: Thiamine contains a substituted pyrimidine ring connected to a substituted thiazole ring by means of methylene bridge. The vitamin is then conveed to its active co-enzyme form by addition of two phosphate groups, with the help of ATP (Fig. 34.1). It is catalyzed by thiamine pyrophosphotransferase. Reference: Vasudevan Textbook of Biochemistry pg no.391', 'role': 'assistant'}]