Sam put his return ticket in a special box. It was where he kept all of his what?
Options:
- airline envelope
- airport
- plane
- tickets
- keepsakes
Let's think carefully first. Step-by-step reasoning process:

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
Sam put his return ticket in a special box where he kept all of his tickets. So the final answer is tickets.