The assumption that the marginal product of labor decreases as the labor input increases implies that

Economic theory is most useful in explaining the operation of social systems

A) aimed at making a living. B) directed toward the satisfaction of material wants. C) in the world of business and finance. D) in which participants characteristically don't know one another personally. E) in which people pursue selfish interests.

In the above figure, what is the marginal social cost to the economy of producing the four-hundredth pretzel?

A) $0 B) $2.00 C) $4.00 D) None of the above answers are correct.