The correct answer is...
C, or the third answer choice. The answer choice B and D are wrong because DNA does not contain the base pair of uracil. Additionally, you must know that C and G come together to make 3 hydrogen bonds, whereas A and T only make 2, and thus, a DNA strand with more Cs and Gs will have a much higher melting point than will one with lots of As and Ts, which is why C is a better answer than A.
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