If the Equilibrium Quantity Is Equal to the Socially Optimal

Multiple Choice

If the equilibrium quantity is equal to the socially optimal quantity, one can infer that:

A) the supply curve for the activity is below the socially optimal supply curve.
B) there is no externality associated with this good.
C) there is a positive externality associated with this good.
D) there is a negative externality associated with this good.