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
Which of the following method of protein separation is not dependent on molecular size ? 
Select and explain. 
A. Gel filtration chromatography, B. Ultracentrifugation, C. Ion-exchange chromatography, D. SDS-PAGE
C: Ion-exchange chromatography
Answer: C: Ion-exchange chromatography 
Explanation: Ans. is 'c' i.e., Ion-exchange chromatography