フリー問題

問題文

A shared directory on a FreeBSD host is writable by every member of a project, but files keep being removed by people who do not own them. The administrator wants only owners to be able to remove their own files there. Which bit does that, and what does it leave alone?

選択肢

1. Only owners can remove their own entries once the execute bit is set on that collaborative directory and the same bit has no effect on the write permission that the directory already grants to the group.
2. Only owners can remove their own entries once the execute bit is set on that collaborative directory and the same bit has no effect on the ownership transfer that the directory already grants to the group.
3. Only owners can remove their own entries once the sticky bit is set on that collaborative directory and the same bit has no effect on the ownership transfer that the directory already grants to the group.
4. Only owners can remove their own entries once the sticky bit is set on that collaborative directory and the same bit has no effect on the write permission that the directory already grants to the group.