Final answer:
To achieve the lowest unit labor costs, a country should use a production technology with the lowest total cost and adjust its workforce towards industries where it has a comparative advantage, considering the relative costs of labor and capital.
Step-by-step explanation:
In general, the combination that would lead to the lowest unit labor costs for one country relative to another would be one where the labor is plentiful and less costly while technology used is efficient yet not expensive. If the cost of machines has increased, as indicated in the scenario, companies would opt for production technology 2 which has the lowest total cost favoring more labor utilization. Conversely, if the cost of machine hours has decreased, firms would likely shift towards production technology 3 due to the decreased expenses associated with capital.
Transferring workers to industries or technologies where a country has a comparative advantage could further decrease unit labor costs. For instance, in an example where the United States moves workers away from shoe production into refrigerator manufacturing, the shift aligns the workforce with an area where the U.S. may be more efficient, thereby lowering costs in that sector and potentially producing more with the same or less labor input.