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': 'Mutation in sickle cell anemia is \nSelect and explain. \nA. Silence, B. Missense, C. Non-sense, D. Frame-shift', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Missense mutation - Sickle cell anaemia.\nNon-sense mutation - Beta thalassemia.', 'role': 'assistant'}]