Answer the Question Based on the Following Information for a Public

Multiple Choice

Answer the question based on the following information for a public good. Pₐ and Pᵦ are the prices that individuals A and B are willing to pay for the last unit of a public good, rather than do without it. These people are the only two members of society. If the marginal cost of producing this good at the optimal quantity is $4, the optimal quantity must be

A) 1 unit.
B) 2 units.
C) 3 units.
D) 4 units.