I was confused about that too.
The correct answer is to choose both of them.
I wasn't really confused by the answers more by the question https://forum.linuxfoundation.org/discussion/857091/renice-command-increasement-by-5#latest
but how I saw it, both set it to 5 since 5 and +5 are both positives.
This has come up in a number of forums. The question should have said which will set it equal to 5, not increase it by 5. I believe it has now been corrected (the + sign is implicit and not needed)
Yes, that's a bug in the document. We'll change that at next course update. In the thread pointed by @dolios you can find the explanation, and also a way to test renice.
it is already changed AFAIK
This question has been corrected. Please clear your cache to see the update.
I've done the quiz yesterday and it was not corrected.