Previously, the nation of Diaturna made heavy use of imported iron in its steel foundries. Recently, Diaturna adopted legislation that would shift its industrial emphasis from the production of steel to the production of aluminum, which does not require iron. At present, Diaturna harvests more aluminum ore than it uses for industrial purposes, and iron procurement from Diaturnan mines is increasing at a predictable rate. If this shift in mining and production continues, therefore, Diaturnan dependence on foreign countries for metal production will soon decline.
Which of the following would it be most useful to establish in evaluating the argument?