The correct answer is Beau, who was raised in Savannah, Georgia.
Now, this is a very stereotypical question, and a bit offensive to ask, but based on these stereotypes, we can deduce that Beau will be the one to engage in physical aggression. It won't be any of the two Asian citizens because they are raised to be polite and mindful of others. It probably won't be Billy either, because he lives in the northern parts of the US. So it will probably be Beau, as he comes from the South which is stereotypically thought to be less educated and refined.