The pairings that correctly match an organization with its function are:
- African Union: resolve conflicts in sub-Saharan Africa
- COMECON: promote trade in Communist Eastern Europe
The other organizations and their functions are not correctly matched:
- The Commonwealth primarily focuses on promoting democracy, development, and cultural ties among its member states, rather than specifically economic advancement in Asia.
- The Warsaw Pact was a military alliance among Eastern Bloc countries, primarily aimed at countering NATO rather than explicitly preventing the spread of Communism.
- The European Union does address various issues, but resolving border disputes specifically is not its primary function; it is more involved with broader integration and cooperation among European states.
Thus, the best-combined responses would be African Union and COMECON.