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': 'The following is an example for unusual base \nSelect and explain. \nA. Di hydro uracil, B. Adenine, C. Cytosine, D. Uracil', 'role': 'user'}, {'content': 'Answer: A \nExplanation: It is present in tRNAPresent in the DHU OR D arm of tRNAServe as the recognition site for the enzyme which adds the amino acidRef: DM Vasudevan, 7th edition, page no: 597', 'role': 'assistant'}]