What does a demand curve represent?

A demand curve illustrates how much of a good or service consumers are willing to purchase at different price levels over a specified time period. Each point on the curve represents a different price and the corresponding quantity that buyers are prepared to buy.

As the price decreases, the quantity demanded typically increases, reflecting the law of demand. This negative relationship is graphically represented with a downward-sloping curve. Understanding the demand curve is vital for analyzing consumer behavior, market equilibrium, and pricing strategies.

The other options do not accurately describe a demand curve: one refers to supply, another focuses on total revenue rather than quantity demanded, and the last implies a relationship between price and output, which commonly pertains to supply rather than demand. Thus, the correct choice highlights the core concept of the demand curve's purpose in economics.