According to the Smith, Ricardo, and Heckscher-Ohlin theories, a country's economy may gain if its citizens buy some products from other nations that could be produced in their home nation. What is the reasoning behind this idea

b. International trade allows a country to specialize in items that can be produced most efficiently in that country.

Explanation:

Adam Smith with his Absolute Advantage theory, David Ricardo and his Comparative Advantage theory and the Heckscher-Ohlin theories believed that goods should be purchased from Countries that are more efficient in producing said goods so that the resources in the buying country can be channelled towards producing the good that the country can produce efficiently as well.

They believe this to be the foundation of global trade and that each country stands to gain if they buy the goods they are less efficient at producing and sell the goods that they are more efficient at producing. This way resources are properly channelled in an Economy and both countries involved in the trade can achieve high Economic growth as they are utilising their resources efficiently.