Final answer:
A common market is the level of economic integration where internal trade restrictions and capital flow barriers are removed among member nations, yet it falls short of political unification.
Step-by-step explanation:
The level of economic integration that includes no restrictions on internal trade and free flow of capital among member nations, but lacks only political unity to become a political union, is known as a common market. Unlike a free trade area, which offers free trade between its members but allows each country to determine its own trade policies outside the association, a common market establishes a common external trade policy as well. This is one step below an economic union, which, in addition to having a common market, coordinates fiscal and monetary policy among member countries.