please answer the following question

Answer the question based on the following Information for a public good. Pa and Pp 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. Q Pa Pb $ 3 $ 5 2 w + AWN + 2 If the marginal cost of producing this good at the optimal quantity is $8, the optimal quantity must be Multiple Choice 1 unit. O 4 units. O 3 units. 2 units. 5 units