Answer this question on the basis of the following information for a public good. pa and pb 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 (qc) of the public good. qs represents the quantity of the public good supplied by government at each of the collective prices. qc pa pb qs 1 $4 $5 5 2 3 4 4 3 2 4 3 4 2 3 2 5 1 2 1 in equilibrium, the marginal benefit and cost of the public good will be a. $7. b. $6. c. $5. d. $3.