In the scenario you described, where a government price control is set at a price \( P_c \) that is below the equilibrium price, the quantity demanded \( Q_1 \) will be greater than the quantity supplied \( Q_2 \). This creates a shortage in the market.
Since \( Q_1 \) represents the quantity demanded at the price ceiling \( P_c \) and \( Q_2 \) represents the quantity supplied at that same price, the difference \( Q_2 - Q_1 \) will illustrate the shortage:
- \( Q_2 - Q_1 \) is negative since \( Q_2 < Q_1 \).
Therefore, the correct description for \( Q_2 - Q_1 \) in this context is "the shortage resulting from the price ceiling \( P_c \)."
Thus, the correct response is:
the shortage resulting from the price ceiling \( P_c \).