😉
It'll be a combination of all of that... ethical dilemmas, hypothetical problems, etc.
I'd say it's generally hard to prepare for these since the prompts vary so much. It really is an exercise designed to see how you think on your feet. I suppose looking into real-world approaches to ethical dilemmas might be a start, but then again there is no uniform answer to a given issue. The methodology you take in your approach is what they're probably looking at--that is know the pros and cons of your argument. Avoid sweeping black and white distinctions etc.
I'm pretty sure they provide scratch paper and a pen to work with (I've had friends who interviewed here in previous cycles).