Final answer:
At the turn of the twenty-first century, ASEAN members shifted their focus towards economic integration similar to that of the European Union, moving away from their initial purpose of countering communism.
Step-by-step explanation:
The new focus of ASEAN members at the turn of the twenty-first century was to emulate the integration seen in the European Union. ASEAN, which was initially established to foster regional development and resist the spread of communism, had achieved considerable success in its goals and sought to replicate the economic integration of the EU. In the 2000s, ASEAN openly advocated for the creation of similar economic integration within Southeast Asia, which indicates that the most accurate answer to the question would be (b) Working with the EU.