Why is the concept of the E. U. known as “single market”?

The single market refers to the EU as one territory without any internal borders or other regulatory obstacles to the free movement of goods and services.

Explanation:

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.

answer; ///he could not explain why the continents drifted;