The correct answer is sentence (5).
A sentence fragment means that it is only a part of a sentence; it is not complete. Given that it is incomplete, the fragment, aka subordinate/dependent sentence, has to be part of a larger, independent sentence, in order to make any sense. So if you combined sentence (5) with another one, it wouldn't be a fragment anymore.
I don't know a lot but I just did a class about this.
But to change perfect past tense completed in the past by changing the verb is or could be by replacing the verb with the action to was ,did ,before, ect. I think this might help
Answer: He follows something
Explanation:
THE ANSWER IS A BCUZ OF REASONS, NOW I GOTSZ FRE POINTS. LOLOLOLOL