This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to hang border wallpaper
Decide where you want to hang your border.
You can hang the border immediately below the ceiling or crown molding, along the top or bottom third of the wall, or halfway down a wall. Choose the location based on your preferences.

Available choices:
[a]. You can hang in a crawl space, or underneath furniture to provide privacy while decorating. Place one end of the border in the corner..
[b]. Clean the area where you want to hang your wallpaper. Use soapy water to thoroughly clean the area where you want to hang the wallpaper..
[c]. Instead of hanging your border at the top or the bottom of the wall, hang your border from the crown molding. This way you can see the whole room..
[d]. For example, if you are hanging a poster of eiffel tower and you simply wish to bring an original icon into your room, you may hang on the front or rear of the wall. If you are hanging a more contemporary hanging, you may want to place your hanging border across the top and bottom third of the wall..
The answer is:
[b].