This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Which base is not found in DNA? \nSelect and explain. \nA. Adenine, B. Guanine, C. Cytosine, D. Uracil', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]