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': 'Leucine is a aminoacid with a \nSelect and explain. \nA. Nonpolar side chain, B. Polar side chain, C. Negatively charged side chain, D. Positively charged side chain', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Leucine is non-polar amino acid, i.e. its side chain (R) is nonpolar.', 'role': 'assistant'}]