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 a-thalassemia, Hb Bas is said when number of gene loci affected is: \nSelect and explain. \nA. 1, B. 2, C. 3, D. 4', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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.', 'role': 'assistant'}]