Suppose That a Private Firm Is Supplying a Collective Good

Suppose that a private firm is supplying a collective good to a market with demand of P = 24 - 3Q.If the marginal cost of providing this good is zero but the firm charges $18,the actual equilibrium output is __________ units,while the socially efficient output is __________ units.

A) 2;8
B) 6;8
C) 2;2
D) 4;2
E) 2;4