Both surfaces of the carbon-impregnated electrodes appear shiny. What might this indicate?
a. The carbon-impregnated electrodes may be clean and free of contaminants
b. The carbon-impregnated electrodes may be of high quality and well-maintained
c. The carbon-impregnated electrodes may have a thin layer of protective coating
d. The carbon-impregnated electrodes may be experiencing a chemical reaction with their environment