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
SDS - PAGE Separater proteins based on: 
Select and explain. 
A. Charge, B. Solubiliy, C. Size, D. Polarity
C: Size
Answer: C: Size 
Explanation: SDS - PAGE imparts equal negative charges, thus nullifying the effect of charge.
It separates proteins purely on the basis of size (molecular weight).