If the Equilibrium Quantity of a Good Is Also the Socially

Multiple Choice

If the equilibrium quantity of a good is also the socially optimal quantity, then:

A) total economic surplus has been maximized.
B) the marginal benefit to consumers of another unit of the good is zero.
C) the marginal cost to producers of another unit of the good is zero.
D) it's possible to make at least one person better off without hurting anyone else.