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: Pathology
[{'content': 'In fanconi anemia, there is a \nSelect and explain. \nA. Deficiency of copper, B. Mutation of DNA repair gene, C. No increased risk of squamous cell carcinoma, D. Purely nutritional disorder etiology', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]