Rising incomes in a city shift the demand curve for rental housing to the right, moving the unconstrained equilibrium from $500 with 15,000 units to $600 with 17,000 units. If the city instead passes a rent control law that fixes the legal price at $500, quantity supplied stays at 15,000 while quantity demanded rises to 19,000 at that price. What results from the rent control law?

1. The rising-income demand shift already happened, so it is not undone by the price ceiling. 2. At the legally fixed price of $500, quantity supplied stays at 15,000 units, since sellers respond only to price and price cannot rise. 3. At that same price, quantity demanded is 19,000 units, since the demand curve already shifted right. 4. Quantity demanded of 19,000 exceeds quantity supplied of 15,000 by 4,000 units, which is a shortage. 5. Option B mislabels the gap as a surplus, which would require quantity supplied to exceed quantity demanded instead. _Source: OpenStax Principles of Macroeconomics for AP Courses (CC BY 4.0), Ch 3 "Demand and Supply", section 3.4 | Price Ceilings and Price Floors_