As I don’t know your parents I can just project from myself: Whoever would be the physically closer one at that precise moment.

I can’t imagine a situation where this could be a rational decision unless one of you fucked them over in a way I can’t even begin to fathom.

This is so deep monked brain territory that it really comes down to pure instinct and that is driven by perceived higher chance.

If the situation is in a way there it’s impossible (for example would have to carry both of you but you’re too heavy) chances would be high that we’d all die together - not because of some heroism bullshit but simply because I know my inner monkey quite well and it’s self preservation instinct vs kin preservation are … Let’s say not in my favor ad an individual :D