Suppose the demand curve for steel is Q = 100 - P, where P is the price per unit of steel and Q measures millions of units of steel. The private marginal cost of producing steel is MC = 5Q + 40, while the external marginal cost of producing steel is $12. In a perfectly competitive steel industry, the deadweight loss is:

A.$750,000.

B. $200,000.

C. $2 million.

D. $12 million.