D. Country should pass tariff laws in order to protect domestic industries from foreign competition.
Adam Smith is known for his reverence on free trade. He believes that an "autopilot mechanism" of the free market will serve all-- both domestic and foreign businessmen and consumers. He does not believe in Mercantilism and concludes that when the government tries to restrict foreign competition, it is actually damaging the consumers by making products (that are better) inaccessible.