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': "Test for β- thalassemia trait - \nSelect and explain. \nA. HbA\n2, B. HbF, C. Fragility test, D. Coomb's test", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]