This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basics of DNA, Subject name: Biochemistry
[{'content': 'At Tm or melting temperature, what percentage of dsDNA is denatured? \nSelect and explain. \nA. 25%, B. 50%, C. 75%, D. 100%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Melting temperature or Tm Temperature when half (50%) of the helical structure is denatured. At lower temperature, the melted strands are re-associated; this is called annealing. When DNA is denatured, unstacking of bases occur resulting in increased absorbance at 260 nm-hyperchromicity', 'role': 'assistant'}]