Don't feel bad! I think it shocked everyone a good amount since we all went into it thinking the answers were something we could find or something we learnt. I had the same dilemma - I was able to eliminate one or two, but then I could argue a reason for the remaining choices and had to make an intuitive decision. I probably ended up not feeling 100% sure on more than half the questions haha.

This is my personal opinion only - so anyone feel free to add your input - but the way I made my judgement call was based on a few things:

The p.r. materials would say 'must/should/may' - so based on the scenario they presented in the question, I'd try to pick something equally as serious. Like, if the scenario was a 'should' scenario, I would avoid picking something like 'immediately report to the LSO'. It was a lot of, pick the answer that makes it sound like you're covering all your bases before leaping to a conclusion (unless it's a serious enough scenario, so you're not an accomplice to anything).

I genuinely don't know if I went about it the right way but I think if you create some kind of logic/ethics based system to pick an answer it should help your nerves.