During gel electrophoresis, restriction enzymes are used to cut DNA into fragments. Those fragments are then added into a well cut from a slab of gel. An electric field is passed through the gel, causing the fragments to migrate to the positively-charged terminal at the other end of the gel. The DNA fragments separate into bands on the gel because A. smaller fragments move through the gel faster than larger ones. B. larger fragments move through the gel faster than smaller ones. C. fragments that contain a high amount of adenine travel the farthest. D. positively-charged fragments move through the gel faster than neutral ones.