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
In a-thalassemia, Hb Bas is said when number of gene loci affected is: 
Select and explain. 
A. 1, B. 2, C. 3, D. 4
D: 4
Answer: D: 4 
Explanation: Answer- D. 4The alpha-thalassemias are caused by inherited deletions that result in reduced or absent synthesis of alpha-globin chains.Normally, there are four alpha-globin genes.