It's the starting point of moral thinking
Any scenario has variance involved with both the person being asked there choices on any given day-night, time, state-of-mind etc that all effect thoughts of moral behavior and,
the specific set of circumstances.
Let say they are all strangers, for and all dressed exactly alike enough that we dont see them as male or female of fat or skinny ergo they might as well be robots dressed like humans for all we know.
Then at last moment we see one is wearing red shoes, and brains pattern of thinking we attach some relevance to red shoes that is sways our decision, one way or the other. Or maybe one of them is wearing glasses. Or has longer hair, or walks differrent from the others.
So much of our preconditioning comes into play in the sour of the moment and even if given days to think about something, we still may be dealing with uncertainty of mind principle.
Moralls is just part of the biologic human processing and my guess rarely overrides preconditioning that may having varing degrees of morality involved.