Which concept refers to the entire relationship between prices and quantity demanded at those prices?

The concept that refers to the entire relationship between prices and quantity demanded at those prices is the demand curve. The demand curve illustrates how much of a good or service consumers are willing to purchase at various price levels, typically showing that as prices decrease, the quantity demanded increases, and vice versa. This relationship is foundational in economics, as it depicts consumer behavior and preferences in response to changing prices.

In contrast, market equilibrium refers to the state where the quantity demanded and the quantity supplied are equal at a particular price, rather than the relationship itself. The supply curve, on the other hand, shows the relationship between prices and the quantity supplied, which is a different focus. Quantity supplied denotes the specific amount of a good or service that producers are willing to sell at a given price, not the broader relationship represented by the demand curve. Thus, understanding the demand curve is crucial for analyzing consumer behavior in relation to price changes.