Answer:
Interest on a national debt
Explanation:
If a government decides to pay the interest on the national debt, that is one of the examples of an opportunity cost which a whole country will abide. For instance, a government pays interest on a debt of 10 million dollars, that money could have been spent on education, health or on building infrastructure such as roads. Governments every now and then make certain decisions which result in a large sum of opportunity cost, and a whole country experiences that.