Which of the following encourages trade between regions?
Differences in currencies of countries
Difference in national income of countries
Existence of trade associations
Differences in natural resources
Correct answer is D
One of the major reasons for trade is the difference in the natural resources of each country. No country is an island of its own, no matter how efficient its production factors may have been utilized.
There is always going to be something the region needs and may have to source for it from its neighbors.