Answer This Question Based on the Following Information for a Public

Answer this question based on the following information for a public good. Pₐ and Pᵦ represent the prices that citizens (a) and (b) , the only two people in this nation, are willing to pay for additional units of a quantity (Q_c ) of the public good. Qₛrepresents the quantity of the public good supplied by government at each of the collective prices. If only 1 unit of this public good is produced, then the marginal benefit is

A) $3, and the marginal cost is $9.
B) $4, and the marginal cost is $7.
C) $6, and the marginal cost is $3.
D) $9, and the marginal cost is $3.