Explanation:

• Option A (A rise in sales taxes): Incorrect. An increase in sales taxes is contractionary, as it reduces disposable income and lowers consumer demand. Expansionary fiscal policy typically involves tax cuts to stimulate demand.

• Option B (A reduction in interest rates): Incorrect. While a reduction in interest rates is expansionary, it falls under monetary policy, not fiscal policy. Fiscal policy involves government spending and taxation.

• Option C (Increased public expenditure on infrastructure): Correct. Expansionary fiscal policy can include increased government spending on infrastructure or social goods to boost aggregate demand and stimulate economic growth.

Key Takeaway: Expansionary fiscal policy aims to increase aggregate demand through government spending or tax cuts, distinguishing it from monetary policy tools like interest rate adjustments.