WHICH QUESTIONS SHOULD YOU ANSWER?
You haven't got a lot of time to spend on this decision - don't spend time dithering about it.
Go For Familiar Topics. It might happen that there's a question on a topic which you've revised, but that the wording of the question isn't what you wanted. Even so, it's better to stay with the topics you've revised rather than go with a new topic because the question on it seems easier. It probably only seems easier because you don't know much about it.
If you stay with the topics you know, you're getting full value for all the revision you've done.
And when you've chosen what your questions will be, or at least what your first one will be, Stick To It. If you start writing on one question, then change your mind half way through, you'll have wasted an awful lot of time.