A city imposes a binding rent ceiling on apartments built before 1990. In the short run with a fixed number of units, what is the most likely effect on the quantity of apartments traded?

• A. Decreases because landlords withdraw apartments from the market, reducing the number traded.
• B. Falls to zero as landlords stop renting out apartments under the ceiling.
• C. Remains unchanged at the fixed number of existing units, creating a shortage (excess demand).
• D. Increases because the lower rent attracts more renters and raises the number of transactions.

Answer: (C)