Which of the following is an example of discretionary fiscal policy? Government builds more hospitals as the population ages. An increase in total unemployment benefit payments during a recession due to rising unemployment. An increase in corporate tax collection during an expansion because of more sales. A decrease in total unemployment benefit payments during expansion due to increasing employment. An increase in the interest rate.

The example of discretionary fiscal policy among the options given is: "Government builds more hospitals as the population ages."

Here's the step by step explanation:

1. Discretionary fiscal policy refers to the deliberate manipulation of taxes and government spending by the government to influence the economy. This is usually in response to changes in economic conditions and it is not automatic.

2. The option "Government builds more hospitals as the population ages" is an example of discretionary fiscal policy because it involves a deliberate decision by the government to increase spending on healthcare infrastructure. This is a conscious decision made by the government to address the needs of an aging population, and it is not an automatic response to economic conditions.

3. The other options involve automatic stabilizers, which are economic policies and programs, such as unemployment benefits and corporate taxes, that are designed to offset fluctuations in a nation's economic activity without intervention by the government or policymakers. These are not examples of discretionary fiscal policy because they happen automatically based on economic conditions.

4. The last option, "An increase in the interest rate," is a monetary policy tool, not a fiscal policy tool. It is used by central banks to control inflation and stabilize the economy. It is not a discretionary fiscal policy.