This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Poly (A) tail translates into \nSelect and explain. \nA. Polyproline, B. Polylysine, C. Polyalanine, D. Polyglycine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A poly (A) tail is added to the 3&; end of the pre-mRNA once elongation is complete. The poly (A) tail protects the mRNA from degradation, aids in the expo of the mature mRNA to the cytoplasm, and is involved in binding <a href=" involved in initiating translation.</li>', 'role': 'assistant'}]