This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'Proteins can be separated by the following except \nSelect and explain. \nA. Electrophoresis, B. Ultra - centrifugation, C. Gas chromatography, D. None', 'role': 'user'}, {'content': 'Answer: D \nExplanation: question repeated', 'role': 'assistant'}]