Astudent isolates a protein from anaerobic bacteria and analyses the protein by polyacrylamide gel electrophoresis containing sds (page-sds). following protein staining, a single band appears, which excites the student's supervisor. to be certain, the supervisor suggests that the student run a second electrophoresis under native conditions (i. e. non-denaturing, or without sds). this gel shows two bands after staining. assuming no errors were committed during these experiments, explain the observations.

a. in the absence of sds, protein subunits separate into two peptide with charges, leading to two peaks.
b. in the absence of sds protein subunits separate into two peptides with different masses, leading to two peaks.
c. in the presence of sds two proteins with identical charges but different molecular weights will show a single band, while in the absence of sds different molecular weights will create separation.
d. in the presence of sds two proteins with identical molecular weight but different isoelectric points will show a single band, while in the absence of sds different charges will create separation.