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': 'A couple with a family history of beta-thalassemia major in a distant relative has come for counseling. The husband has HbA2 of 4.8% and the wife has HbA2 of 2.3%. The risk of having a child with beta-thalassemia major is: \nSelect and explain. \nA. 50%, B. 25%, C. 5%, D. 0%', 'role': 'user'}, {'content': 'Answer: D \nExplanation: HBA2 of 4.8% indicates beta thalassemia minor or trait.\nHbA2 of 2.3% indicates normal person.\nThalassemia is an autosomal recessive disorder. Therefore, when a trait marries a minor, then the risk of having children with thalassemia major is 0%.', 'role': 'assistant'}]