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: Medicine
[{'content': 'The most impoant diagnositic feature for beta thalassemia trait \nSelect and explain. \nA. Raised HbF, B. Reduced MCH, C. Reduced MCV, D. Raised HbA2', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Raised HbA2", 'role': 'assistant'}]