Its a choice trap where Superman has to choose to save his best friend in the whole world or saving a stranger.
The rules are:
He can only save one person despite all his powers and if he doesn't decide they both die.
Also to make things interesting,no time travelling,no reversing time to undo the event,no parallel universe travel to effect the current universe,no helping from anyone.
He is alone to make the decision
So how will he act?