In Teruvia, the quantity of rice produced per year is currently just large enough to satisfy domestic demand. Teruvia's total rice acreage will not be expanded in the foreseeable future, nor will rice yields per acre increase appreciably. Teruvia's population, however, will be increasing significantly for years to come. Clearly, therefore, Teruvia will soon have to begin importing rice.
Which of the following is an assumption on which the argument depends?