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': 'All of the following bases are present in DNA, EXCEPT: \nSelect and explain. \nA. Adenine, B. Guanine, C. Uracil, D. Thymine', 'role': 'user'}, {'content': "Answer: C \nExplanation: DNA contains only four different bases: adenine (A), guanine (G), thymine (T), and cytosine (C). DNA exists as a double helix in which A is always paired with T, and G is always paired with C. RNA contains the ribonucleotides of adenine, guanine, and cytosine, it does not possess thymine. Instead of thymine, RNA contains the ribonucleotide of uracil. Ref: Weil P. (2011). Chapter 34. Nucleic Acid Structure & Function. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.", 'role': 'assistant'}]