Which graphical representation illustrates a demand schedule?

The demand curve is the correct representation of a demand schedule because it visually depicts the relationship between the price of a good and the quantity demanded by consumers at those various price levels. A demand schedule itself is a table that lists different prices alongside the corresponding quantities of a product that consumers are willing to purchase at those prices. When this data from the demand schedule is plotted on a graph, the result is a demand curve, which typically slopes downward from left to right, illustrating the inverse relationship between price and quantity demanded.

The demand curve effectively summarizes the information outlined in the demand schedule in a graphically intuitive manner, making it easier to analyze changes in demand based on price fluctuations. This visual tool allows economists and decision-makers to forecast consumer behavior more accurately.

The other options do not serve this purpose. A demand diagram might refer to various forms of representing demand, but is not specific to the demand schedule. A diminishing returns graph focuses on production inputs and outputs, illustrating different concepts in production theory, and a supply curve represents the relationship between price and quantity supplied, not demanded. Thus, the demand curve is the most appropriate choice for illustrating a demand schedule.