Where would you display a picture on a vertical surface?
Options:
- shelf
- desktop
- editer
- wall
- art show
Please answer and provide answer explanation.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
A wall is a vertical surface. People often hang pictures on the wall. The final answer: wall.