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: Biochemistry
[{'content': 'Sickle cell anemia is the clinical manifestation of homozygous genes for an abnormal haemoglobin molecule. The event responsible for the mutation in the B chain is - \nSelect and explain. \nA. Inseion, B. Deletion, C. Non disj unction, D. Point mutation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. point mutation', 'role': 'assistant'}]