Which factor can lead to a shift in the supply curve?

A shift in the supply curve occurs when a change in economic factors affects the quantity producers are willing and able to sell at various price levels, independent of any change in price itself. A change in the cost of production is significant because it directly impacts producer profitability. For instance, if production costs decrease due to lower prices for raw materials or improved technology, producers are able to supply more at every price point; hence, the supply curve shifts to the right. Conversely, if production costs increase, this would lead to a reduction in supply, shifting the curve to the left.

Other factors mentioned, such as increases in consumer income or changes in consumer preferences, primarily influence demand rather than supply. Furthermore, while the number of products on the market might relate to overall market dynamics, it does not inherently change the production costs or the willingness of existing producers to supply a given good or service. Therefore, understanding how changes in production costs shift the supply curve is critical in analyzing market movements.