Which sentence uses an appropriate transition to add additional support for a main idea?
1. Thorough hand-washing prevents illness by killing germs on the hands; and yet, cleaner hands are less likely to spread contamination to other surfaces.
2. Thorough hand-washing prevents illness by killing germs on the hands; thus, cleaner hands are less likely to spread contamination to other surfaces.
3. Thorough hand-washing prevents illness by killing germs on the hands; in addition, cleaner hands are less likely to spread contamination to other surfaces.
4. Thorough hand-washing prevents illness by killing germs on the hands; in summary, cleaner hands are less likely to spread contamination to other surfaces.