Which of the following factors contributes to a shift in short-run aggregate supply?

A shift in short-run aggregate supply is influenced by changes in production costs, which include wages, input prices, and overall economic conditions affecting how businesses operate in the short term. Changes in wage expectations are particularly impactful because they directly affect the cost of labor. When workers expect higher wages, businesses may face increased costs, leading them to reduce supply at current price levels. This situation would shift the short-run aggregate supply curve to the left, indicating a decrease in the quantity of goods and services supplied at given price levels.

In contrast, changes in consumer income levels primarily affect aggregate demand rather than aggregate supply. Likewise, changes in fiscal policy can influence overall economic activity and aggregate demand more directly, as they typically involve government spending and taxation changes. Changes in foreign exchange rates can impact aggregate demand by making exports cheaper or more expensive for foreign buyers, but they do not directly shift the short-run aggregate supply curve. Therefore, changes in wage expectations are the key factor that leads to shifts in the short-run aggregate supply.