Final answer:
Differences in opportunity costs between industries (option d) are key to achieving comparative advantage. This allows countries to specialize in the production of certain goods and trade to increase global efficiency and consumption.
Step-by-step explanation:
A key consideration in determining whether a country can achieve a comparative advantage is not rooted in the country's absolute advantage in all industries nor in its population size, or the mere availability of cheap labor. Instead, it is differences in opportunity costs between industries that are most significant. Comparative advantage exists when a country can produce a good at a lower opportunity cost in terms of other goods, compared to other countries. It is this principle that allows countries to specialize and gain from trade, which increases global production and levels of consumption for all involved.
Absolute advantage refers to the scenario where a country has a productivity edge over another, requiring fewer resources to produce a product. However, a country can have an absolute advantage in producing all goods and still benefit from trade through comparative advantages. Specialization in the production of goods where a country has the lowest opportunity cost, and trading for goods where others have comparative advantages, optimizes global efficiency and consumption. The classic example involves Britain having a comparative advantage in cloth and the United States in wheat production, due to each having a lower opportunity cost in those respective goods.