This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiotherapy, Subject name: Radiology
[{'content': 'Which part of DNA is most susceptible to radiation? \nSelect and explain. \nA. Nucleotides, B. Nucleosides, C. Histones, D. Double helix', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (D) Double helix > Relatively flexible areas of the DNA double helix are most susceptible to damage.> Radiation can damage the DNA "double helix" - a two-stranded, twisting molecule - in a variety of ways: 1) by knocking off one or more of the DNA "bases" known by the letters A, T, G, and C, which form the bonds between the two strands of the double helix; 2) by oxidizing these bases; or 3) by breaking through one or both strands. All can result ir a failure of the molecule to perform its main task - telling cells which proteins to make. That can lead to out-of-control cell growth (cancer) or death.', 'role': 'assistant'}]