Which of the following factors does NOT directly impact demand?

Production costs do not directly impact demand; rather, they primarily affect the supply side of the market. Demand refers to consumers' desire for a product at various price points, while production costs relate to the expenses incurred by producers to create that product. Changes in production costs may lead to changes in supply, affecting overall market equilibrium, but they do not directly influence how much of a product consumers are willing to buy at a given price.

In contrast, consumer expectations, the price of complementary goods, and the number of buyers in the market are all intrinsic factors that directly influence demand. When consumers expect prices to rise, for example, they may purchase more now, increasing current demand. Similarly, if the price of complementary goods goes up, the demand for the primary goods they complement may decrease. Lastly, an increase in the number of buyers can directly lead to an increase in demand for goods and services, as more consumers in the market typically lead to higher overall purchasing levels.