Considering Serum Protein Electrophoresis Using an Agarose Gel Medium, the Main

Considering serum protein electrophoresis using an agarose gel medium, the main purpose of the medium is:

A) to allow electrophoretic migration of proteins to occur
B) to provide a site to bind the protein to, once separation is complete
C) to bind the stain for visualization of the separated proteins
D) to prevent other macromolecules, such as lipids, from interfering with serum protein electrophoresis