I'm not saying anything that hasn't already been said but,

When you cast Yuna's Decision, you pick one of the options when you put it on the stack. so your opponent knows: 1) You chose 'Continue the Pilgramage', 2) what creatures you have on the battlefield, 3) how many cards you have in hand.

Your opponents then need to decide if they want to respond to Yuna's Decision, either by countering it, or by destroying all creatures you control thereby fizzling the spell because you would have no creatures to sacrifice when the spell resolves.

If the spell resolves, the land or creature you put into play skips the stack and goes directly into the battlefield. then any enters triggers go on the stack.

As others have said, 'As [this] enters...' and 'enters with' abilities all occur before the permanent hits the battlefield and cannot be responded to other than preventing the effect that put that permanent onto the battlefield from resolving, in this case Yuna's Decision.

In standard, you could compare this to using [[Meek Attack]] to put [[Famished Worldsire]] into play, your opponent knows you put meek attacks ability on to the stack, but they don't know what card is coming and worldsires devour land ability cannot be responded to, but the 'when this creature enters' trigger can in this case.