Wierd scenarios are 100% legal.
No, they are not. You are not gods over the void between chapters; I am. Thus, no weird situations with rules made up as you go along. They are not going to answer; they're just going to stare at you like the psychopath you will naturally appear to be if you try to proclaim yourself God and announce you are going to make Mark hang over a boiling pot of magma.
This falls under the same category as the rule noted in the first post about how you can't tell the characters important information they don't know in the story; the moment you give them important information, or put them through traumatic experiences, or physically harm them, they will begin deviating from their in-story selves. Odds are actually
, if you put them in that situation, they would all be too scared out of their wits to actually do anything sensible, owing to the fact that they're twelve-year-old kids and all, and while me being me I'd probably find that interesting to write about anyway, I would not do that here in this thread where everything is in script format, and since I like to keep something of a context between individual answers in this thread, I can't just give them all PTSD and make them continue to answer questions that way.
Aside from that, May already told you that if the situation were somehow set up so that a third option couldn't be taken, she'd (in theory) save Spirit rather than Mark, which should be your answer.
That said, it is also pretty pointless to minimod, since it's not as if I'll miss anything that goes on here.