Suppose That Scott's Demand for a Public Good Is P

Suppose that Scott's demand for a public good is P = 7 - 0.3Q and that Mike's demand is P = 10 - 1.5Q.The marginal cost is $14.At the optimal quantity of provision,the marginal benefit of the public good to Scott is about

A) 0.5 units.
B) 1.67 units.
C) $0.50.
D) $2.
E) $6.50.