Philosophy 101 all up in here. It's a dumb question that is phrased poorly.
anyway, I wouldn't kill the kid, because life is suffering. Killing the kid is equatable to killing all humanity. It is impossible to live as a society without suffering at some point. If there's no suffering, we are essentially just sitting around in mindless bliss, and that's no way to live.
If it were more specific, like, if you kill this kid, you end the genocide in Sudan, THAT is a much more compelling debate, to me.