Consider a profit-maximizing monopoly pricing under the following conditions: the profit-maximizing price charged for goods produced is $14; the intersection of the marginal-revenue and marginal-cost curves occurs where output is 10 units and marginal cost is $8; and the socially efficient level of production is 12 units. The demand curve and marginal-cost curves are linear. What is the deadweight loss?

a. $4

b.$6

c.$12

d.$16