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: Skin
[{'content': 'A child develop skin tumor ss na blisters on exposure to sunlight. Irregular dark spots on the skin were also found. He is very likely has defect in which of the following mechanism \nSelect and explain. \nA. Thymidine dimmers repair, B. Base excision repair, C. Mismatch repair, D. Double strand break repair', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. Thymidine dimmers repair', 'role': 'assistant'}]