This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Beta thalasemmia, Subject name: Pathology
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: 
Select and explain. 
A. 50%, B. 25%, C. 5%, D. 0%
D: 0%
Answer: D: 0% 
Explanation: - Normal percentage of HbA2 ranges from 1.5 to 3%. - In thalassemia trait (b thalassemia minor), HbA2 level may be elevated (3.5-7.5%). - Thus, wife in this question has normal genotype (b,b) whereas husband has thalassemia - trait (b+,b). - b-Thalassemia is an autosomal recessive disease. So, None of the offsprings will have thalassemia major (b+ b+), risk of having a child with thalassemia major is 0%. 50% of the offspring (b+,b) will be carriers like father.