What factors influence the costs of supplying such public goods as police protection and national defense?

What factors influence the costs of supplying such public goods as police protection and national defense? What might cause these costs to go up or down, and how would such change affect your taxes?Question: What factors influence the costs of supplying such public goods as policeprotection and national defense? What might cause these costs to go up or down, and how wouldsuch change affect...