Which of the following can lead to a leftward shift in the short-run aggregate supply curve?

A leftward shift in the short-run aggregate supply curve occurs when production becomes more difficult or expensive, leading to a decrease in the quantity of goods supplied at any given price level. An increase in input costs is a significant factor that directly contributes to such a shift.

When input costs rise—whether due to higher prices for raw materials, wages, or energy—producers face increased expenses in the production process. This prompts them to reduce the quantity of goods supplied at existing prices because it is less profitable to maintain previous output levels. As a result, the short-run aggregate supply curve shifts to the left, indicating a decrease in supply at every price level.

In contrast, factors such as decreased labor market participation, improved productivity, or increased savings rates do not directly lead to a leftward shift of the short-run aggregate supply. Decreased labor participation might result in a tighter labor market, but it does not necessarily imply higher production costs. Improved productivity typically contributes to an outward shift in supply as firms can produce more at lower costs. Increased savings rates generally influence aggregate demand rather than supply in the short run, as they affect consumer spending and investment decisions.