For example this one:
You may notice that the text "Active: today" in your screenshot actually contains a hyperlink - if you click on it it goes to the answer that was edited. (In other cases it might go to the question - depending on what caused the bumping.) Also if you see the question in some list of the question which is sorted by recent activity, you can see there "modified 9 hours ago" - if you click on this text, you get the same link. (For other question you can see "answered n hours ago" or "asked n hours ago" - depending on what was the most recent type of activity.)
Then when you view the answer, you can see how it was changed (how it caused bumping) by looking at the timeline. You can also see the text "edited 9 hours ago" - if you click on this text, you can see the revision history.
I will add that in some cases the reason for bumping question might be tied to an answer that is now deleted. In such cases, the reason for bumping might be hidden from users who cannot see deleted answer.
- What is the active link for on the right side of a question
- What can cause a question to be bumped?
- Add link to most recent activity of a question and Recent feature changes to Stack Exchange in February 2010
- The tag-info for last-activity on Meta Stack Exchange.
The reason the 5 year old question shows up again is because it has recent activity. This answer was edited 15 minutes before you asked this question on meta.
On the Questions page you can change the sorting order to newest questions. On the frontpage you can choose between "interesting" and "hot" questions, where this one may still show up because of its 10 upvotes.