Answer:
B. comparative advantage.
Step-by-step explanation:
Comparative advantage tend to be determined by the type of resources that a country possess in abundance. If a country possess a certain type of materials in large quantity, the cost of producing all products that require that material will be significantly cheaper compared to the products with scarce material.
Most countries in the world applied the concept of comparative advantage to a certain extend. They can focus their resources on producing smaller amount of products and purchase the rest of their needs from another country.
As another example, let's examine Saudi Arabia and Japan.
Saudi Arabia have an abundance of oil in their region. They could produce all oil-related product at significantly cheaper cost compared to Japan. So, they decided to focus their effort on maximizing oil production and reduce the production in electronic product.
Saudi Arabia can sell their oil to obtain a lot of profit and could easily purchase the electronic products from Japan without having to produce them by their own.