7. The following information is for a public good. P and P, 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. Refer to the data below. If the marginal cost of this good at the optimal quantity is $4, the optimal quantity must be: OPP 1 $3$s 224 31 31 02 011 A. 1 unit. B. 2 units. C. 3 units. D. 4 units