Don't worry about it too much.
This question is a good intro to the concept but shouldn't be a challenge once you're more familiar with the concept.
This question delves into the complications of a concept but doesn't pose a challenge long-term.
This question is tricky! You may not get it first go, take your time. However, it's not quite exam level.
This question is the Holy Grail –– what you should expect on an examination. Good prep –– you may want to save it for review.