You can prevent one event from happening. Which do you choose.

[Iceglow]

You know, it was up in the air between the best friend and the town. Then I imagined the question was about my wife or one of my kids instead of my best friend, and the choice became obvious.

Another fun question like this is:

A train is about to hit a bus filled with 100 people, killing all of them. You can switch the track but that means the train would instead run into a small boy playing on the other track, killing him. Do you switch it?

This is an interesting one since it deals with the consequences of action vs. inaction. More people die if you don't act, but at least you did not directly have a hand in their deaths. However, killing the boy would be entirely based on your action.

In your scenario, do you have a physical connection to the boy? Or anyone in the 100 on the other track?

If not, then you would end up saving the most amount of lives. Logically it comes down to that. If you have a connection, then you would probably save the person/persons you have the connection to.