The answer is the last one (E): Electrophoresis.
Explanation for each option:
A. Leukapheresis - Incorrect. Leukapheresis is a procedure used to separate white blood cells from a sample of blood, not serum proteins.
B. Hemolysis - Incorrect. Hemolysis refers to the breaking down of red blood cells, which is not related to separating serum proteins by electrical charge and size.
C. Coagulation time - Incorrect. Coagulation time is a measure of how long it takes for blood to clot, not a method for separating serum proteins.
D. Plasmapheresis - Incorrect. Plasmapheresis is a process that removes plasma from the blood, not a method for separating proteins by charge and size.
E. Electrophoresis - Correct. Electrophoresis is a technique used to separate molecules, such as serum proteins, based on their size and electrical charge by applying an electric field.
In summary, electrophoresis is the correct method for separating serum proteins by electrical charge and size.