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': 'Pyrimidine dimers are seen in: \nSelect and explain. \nA. Xeroderma pigmentosum, B. Alkylating agents, C. X-rays, D. Gamma rays', 'role': 'user'}, {'content': 'Answer: A \nExplanation: DNA\xa0damaging\xa0agent\xa0that\xa0results\xa0in pyrimidine dimer is U-V light chemicals:\n\nDNA repair mechanism that repair pyrimidine dimer is Nucleotide Excision repair.\nDefective\xa0Nucleotide\xa0excision\xa0repair\xa0mechanism causes\xa0Xeroderma\xa0pigmentosum, Cockayne Syndrome, Trichothiodystrophy.\nSo, pyrimidine dimers are seen in disorders caused by defective nucleotide excision repair.\n\nReference- Harper 30th edition Pg - 390', 'role': 'assistant'}]