Used to determine how much of a good to buy or sell.

• A. Demand Curve
• B. Inventory Level
• C. Price Ceiling
• D. Market Signal

Answer: (D)

Prices act as market signals that tell buyers and sellers how much of a good to buy or sell. When prices rise, buyers typically reduce purchases while sellers are encouraged to offer more, and when prices fall, purchases rise and production may slow. This signaling helps allocate resources and set actual quantities in the market more directly than a simple representation of demand or an on-hand inventory level. A price ceiling can interfere with these signals by capping prices, which is why the underlying idea—prices as information guiding decisions about how much to buy or sell—best fits.