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
Separation of proteins based on size is done by 
Select and explain. 
A. Affinity chromatography, B. SDS-Polyacrylamide gel electrophoresis, C. Ion exchange chromatography, D. High performance liquid chromatography
B: SDS-Polyacrylamide gel electrophoresis
Answer: B: SDS-Polyacrylamide gel electrophoresis 
Explanation: None