Is a political and economic alliance composed of 27 member nations in Europe:

The European Union is the economic and political alliance composed of 27 member nations in Europe.

Explanation:

The European Union is primarily a political and economic alliance in Europe. As an alliance, it dominates Europe in every aspect, but it is also one of the major global powers. It is an alliance that has very thin boundaries between the actual sovereignty of the countries and the control from the seat in Brussels.

The European Union was formed in the years after WWII as an economic alliance but has grown significantly over the years with a lot of new members joining in, thus increasing its territory and power. Each member nation has to accept and obey a set of rules and decisions made by the EU's government, thus losing part of its sovereignty with it. The alliance seems to be trying to totally erase borders and ethnicity in order to create a single European identity, but also seems to be trying to copy the system by which the United States function.

iii. and iv. only is the right answer