Multi-choice problem: Continue writing the next sentence in this paragraph:

How to keep your school clean
Wipe your feet on mats before you enter the school building.
Dirt, pollen, and leaves can all be tracked in by students' feet, making the floors look dirty. Help keep this from happening by wiping your feet before you come in the door.

Options are: [-] If you notice dirt on mats you can't wipe off, use an absorbent film. This will help it stick better to your feet. [-] If your school doesn't have mats, lightly scuff your feet on the sidewalk before you walk inside. Ask your principal about getting mats if your school doesn't have any. [-] Use a towel after you get inside. Many students leave their feet wet in class. [-] This way, you won't accidentally leave dust behind or rat in your classroom. Be sure to use enough water in a bowl to give students two cups per day, or more if they tend to get dirty between classes.
If your school doesn't have mats, lightly scuff your feet on the sidewalk before you walk inside. Ask your principal about getting mats if your school doesn't have any.