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 of the following are Pyrimidine bases? \nSelect and explain. \nA. Adenine and Guanine, B. Guanine and Cytosine, C. Cytosine and Adenine, D. Thymine and Cytosine', 'role': 'user'}, {'content': "Answer: D \nExplanation: In DNA and RNA, Pyrimidine bases form hydrogen bonds with their complementary purines. Thus, in DNA, the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively. In RNA, the complement of adenine (A) is uracil (U) instead of thymine (T), so the pairs that form are adenine: uracil and guanine: cytosine. Ref: Rodwell V.W. (2011). Chapter 32. Nucleotides. 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'}]