The European Union（EU）is an organization of 15 _____ that promotes cooperation among its members.
A、European countries
B、developed countries
C、Western European countries
D、Southern European countries
【正确答案】：C
【题目解析】：欧洲联盟(欧盟)是一个由15个西欧国家组成的组织，旨在促进成员国之间的合作。
