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': 'The two strands of DNA are held together by \nSelect and explain. \nA. Van-der-Waal bond, B. Hydrogen bond, C. Covalent bond, D. Ionic interaction', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Two strands of DNA are held together by hydrogen bonds between complementary pairs of bases.', 'role': 'assistant'}]