This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Apa from occurring in nucleic acids, pyrimidines are also found in \nSelect and explain. \nA. Theophylline, B. Theobromine, C. Flavin mononucleotide, D. Thiamine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Thiamin (vitamin B1) consists of two components: the pyrimidine moiety (4-amino-5-hydroxymethyl-2-methylpyridine) and the thiazole moiety (5-(2-hydroxyethyl)-4-methyl thiazole).The thiazole and pyrimidine moieties are biosynthesized separately and then combined to form ThMP by the action of thiamine-phosphate synthase', 'role': 'assistant'}]