Explain simply why most buildings is the correct answer to: Dust accumulates where?
Options:
- ceiling
- library
- surface of earth
- most buildings
- desktop. 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
Dust accumulates on most building. Not cleaning frequently allows dust to get accumulated. Building are not cleaned from outside frequently.