Which of the following is NOT a factor that shifts the demand curve?

The correct answer is that input prices do not shift the demand curve. Instead, input prices are a factor that affects the supply side of the market. The demand curve represents the relationship between the price of a good and the quantity demanded by consumers, while the supply curve relates to how much producers are willing to sell at various prices.

Factors that shift the demand curve typically include income changes, the number of buyers in the market, and the prices of related goods. An increase in consumer income, for example, usually increases demand for normal goods, shifting the demand curve to the right. Similarly, an increase in the number of buyers generally leads to an increase in total demand. The prices of related goods, such as substitutes and complements, can also impact demand; for example, if the price of a substitute rises, demand for the original good is likely to increase.

In contrast, changes in input prices influence how much of a good suppliers are willing to produce and sell at various prices, thus affecting the supply curve rather than the demand curve. This distinction is crucial for understanding market dynamics and how different factors interact to determine price and quantity in the market.