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': 'Proteins are separated on the basis of size by: \nSelect and explain. \nA. SDS-PAGE, B. HPLC, C. Affinity Chromatography, D. Ion-exchange Chromatography', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. SDS- PAGE', 'role': 'assistant'}]