Being told whether or not something is true is not the same thing as having it proved for you. If you don't prove it, there's always an element of doubt.
So, I make the assumption that any one of those would be proved upon selection. Given that, I'd immediately rule out a few of them.
is there intelligent life on other planets?
We are too far away from any intelligent life to ever meet it face to face, let alone communicate remotely. We can safely assume that we are NOT unique, that sentient life has, does, and will exist elsewhere in the universe. Given the sheer number of celestial bodies and planets that could support life, we are definitely not the only sentient life in the universe. How would you prove this? Would I be shown a primitive humanoid tribe eating around a campfire on some planet somewhere else in the galaxy? Or perhaps a long distance space faring species traveling in some amazing vessel far beyond our technology? I'd be pretty disappointed to see the ape folks, but hugely impressed to see the space travelers... and yet, also extremely disappointed knowing we'd never meet them. So, this isn't a useful question for me to ask.
is there an afterlife?
Well, this is quite possibly a wasted question, because if there is no afterlife you've not improved your outcome at all. And you can bet that if there isn't, then there isn't a God either. I wouldn't bother asking it.
is there a God?
This is the heavy duty lottery question with a 50/50 chance of "winning." If there is a God, the proof would be a divine personal visit. And that would be a major life changing event. Also, I'd assume you'd get a chance to chat as part of the verification... and then of course the next logical question would be "Of all the religious writings that have been crafted, which one do you truly sanction, Lord?" And if there isn't? Well... I sure hope there isn't an afterlife either.
is time travel possible?
This is a wasted question because we all know that time travel *IS* possible. We know from the way astrophysics works that you could time travel forward by positioning yourself close to a black hole. I suspect you meant "Is time travel
into the past possible?" And you know what? I don't want to know.
So for me, I'd ask the God question.